Rename DisplayController to WindowTreeHostManager

This class manages WTH <-> display mapping, and WTHManager is more appropriate than DisplayController.

BUG=None

Review URL: https://codereview.chromium.org/1262483003

Cr-Commit-Position: refs/heads/master@{#340624}

59 files changed, 556 insertions, 503 deletions

diff --git a/ash/accelerators/accelerator_controller.cc b/ash/accelerators/accelerator_controller.cc
index 2884ec1..7f01b369 100644
--- a/ash/accelerators/accelerator_controller.cc
+++ b/ash/accelerators/accelerator_controller.cc
@@ -12,9 +12,9 @@
 #include "ash/accelerators/debug_commands.h"
 #include "ash/ash_switches.h"
 #include "ash/debug.h"
-#include "ash/display/display_controller.h"
 #include "ash/display/display_manager.h"
 #include "ash/display/display_util.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/focus_cycler.h"
 #include "ash/gpu_support.h"
 #include "ash/ime_control_delegate.h"
@@ -550,7 +550,7 @@ void HandleSilenceSpokenFeedback() {
 
 void HandleSwapPrimaryDisplay() {
   base::RecordAction(UserMetricsAction("Accel_Swap_Primary_Display"));
-  Shell::GetInstance()->display_controller()->SwapPrimaryDisplay();
+  Shell::GetInstance()->window_tree_host_manager()->SwapPrimaryDisplay();
 }
 
 bool CanHandleCycleUser() {
@@ -599,7 +599,7 @@ void HandleToggleCapsLock() {
 
 void HandleToggleMirrorMode() {
   base::RecordAction(UserMetricsAction("Accel_Toggle_Mirror_Mode"));
-  Shell::GetInstance()->display_controller()->ToggleMirrorMode();
+  Shell::GetInstance()->window_tree_host_manager()->ToggleMirrorMode();
 }
 
 void HandleToggleSpokenFeedback() {
diff --git a/ash/ash.gyp b/ash/ash.gyp
index 13d84ce..884b73b 100644
--- a/ash/ash.gyp
+++ b/ash/ash.gyp
@@ -69,8 +69,8 @@
       'display/display_change_observer_chromeos.h',
       'display/display_configurator_animation.cc',
       'display/display_configurator_animation.h',
-      'display/display_controller.cc',
-      'display/display_controller.h',
+      'display/window_tree_host_manager.cc',
+      'display/window_tree_host_manager.h',
       'display/display_error_observer_chromeos.cc',
       'display/display_error_observer_chromeos.h',
       'display/display_info.cc',
@@ -796,7 +796,7 @@
       'dip_unittest.cc',
       'display/cursor_window_controller_unittest.cc',
       'display/display_change_observer_chromeos_unittest.cc',
-      'display/display_controller_unittest.cc',
+      'display/window_tree_host_manager_unittest.cc',
       'display/display_error_observer_chromeos_unittest.cc',
       'display/display_info_unittest.cc',
       'display/display_manager_unittest.cc',
diff --git a/ash/content/display/screen_orientation_controller_chromeos.cc b/ash/content/display/screen_orientation_controller_chromeos.cc
index 0e63f65..8901032 100644
--- a/ash/content/display/screen_orientation_controller_chromeos.cc
+++ b/ash/content/display/screen_orientation_controller_chromeos.cc
@@ -79,7 +79,7 @@ ScreenOrientationController::~ScreenOrientationController() {
   content::ScreenOrientationProvider::SetDelegate(NULL);
   Shell::GetInstance()->RemoveShellObserver(this);
   chromeos::AccelerometerReader::GetInstance()->RemoveObserver(this);
-  Shell::GetInstance()->display_controller()->RemoveObserver(this);
+  Shell::GetInstance()->window_tree_host_manager()->RemoveObserver(this);
   Shell::GetInstance()->activation_client()->RemoveObserver(this);
   for (auto& windows : locking_windows_)
     windows.first->RemoveObserver(this);
@@ -232,12 +232,12 @@ void ScreenOrientationController::OnMaximizeModeStarted() {
   if (!rotation_locked_)
     LoadDisplayRotationProperties();
   chromeos::AccelerometerReader::GetInstance()->AddObserver(this);
-  Shell::GetInstance()->display_controller()->AddObserver(this);
+  Shell::GetInstance()->window_tree_host_manager()->AddObserver(this);
 }
 
 void ScreenOrientationController::OnMaximizeModeEnded() {
   chromeos::AccelerometerReader::GetInstance()->RemoveObserver(this);
-  Shell::GetInstance()->display_controller()->RemoveObserver(this);
+  Shell::GetInstance()->window_tree_host_manager()->RemoveObserver(this);
   if (current_rotation_ != user_rotation_)
     SetDisplayRotation(user_rotation_, gfx::Display::ROTATION_SOURCE_USER);
 }
diff --git a/ash/content/display/screen_orientation_controller_chromeos.h b/ash/content/display/screen_orientation_controller_chromeos.h
index 32d78fb..b387198 100644
--- a/ash/content/display/screen_orientation_controller_chromeos.h
+++ b/ash/content/display/screen_orientation_controller_chromeos.h
@@ -8,7 +8,7 @@
 #include <map>
 
 #include "ash/ash_export.h"
-#include "ash/display/display_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/shell_observer.h"
 #include "base/macros.h"
 #include "base/observer_list.h"
@@ -36,7 +36,7 @@ class ASH_EXPORT ScreenOrientationController
       public aura::WindowObserver,
       public chromeos::AccelerometerReader::Observer,
       public content::ScreenOrientationDelegate,
-      public DisplayController::Observer,
+      public WindowTreeHostManager::Observer,
       public ShellObserver {
  public:
   // Observer that reports changes to the state of ScreenOrientationProvider's
@@ -96,7 +96,7 @@ class ASH_EXPORT ScreenOrientationController
   bool ScreenOrientationProviderSupported() override;
   void Unlock(content::WebContents* web_contents) override;
 
-  // DisplayController::Observer:
+  // WindowTreeHostManager::Observer:
   void OnDisplayConfigurationChanged() override;
 
   // ShellObserver:
diff --git a/ash/desktop_background/desktop_background_controller.cc b/ash/desktop_background/desktop_background_controller.cc
index ed7414e..f1bdc03 100644
--- a/ash/desktop_background/desktop_background_controller.cc
+++ b/ash/desktop_background/desktop_background_controller.cc
@@ -53,12 +53,12 @@ DesktopBackgroundController::DesktopBackgroundController()
     : locked_(false),
       desktop_background_mode_(BACKGROUND_NONE),
       wallpaper_reload_delay_(kWallpaperReloadDelayMs) {
-  Shell::GetInstance()->display_controller()->AddObserver(this);
+  Shell::GetInstance()->window_tree_host_manager()->AddObserver(this);
   Shell::GetInstance()->AddShellObserver(this);
 }
 
 DesktopBackgroundController::~DesktopBackgroundController() {
-  Shell::GetInstance()->display_controller()->RemoveObserver(this);
+  Shell::GetInstance()->window_tree_host_manager()->RemoveObserver(this);
   Shell::GetInstance()->RemoveShellObserver(this);
 }
 
diff --git a/ash/desktop_background/desktop_background_controller.h b/ash/desktop_background/desktop_background_controller.h
index ebebeaa..a06a3fd 100644
--- a/ash/desktop_background/desktop_background_controller.h
+++ b/ash/desktop_background/desktop_background_controller.h
@@ -6,7 +6,7 @@
 #define ASH_DESKTOP_BACKGROUND_DESKTOP_BACKGROUND_CONTROLLER_H_
 
 #include "ash/ash_export.h"
-#include "ash/display/display_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/shell_observer.h"
 #include "base/basictypes.h"
 #include "base/files/file_path.h"
@@ -37,7 +37,7 @@ class DesktopBackgroundControllerObserver;
 
 // Updates background layer if necessary.
 class ASH_EXPORT DesktopBackgroundController
-    : public DisplayController::Observer,
+    : public WindowTreeHostManager::Observer,
       public ShellObserver {
  public:
   class TestAPI;
@@ -87,7 +87,7 @@ class ASH_EXPORT DesktopBackgroundController
   // Returns true if the desktop moved.
   bool MoveDesktopToUnlockedContainer();
 
-  // DisplayController::Observer:
+  // WindowTreeHostManager::Observer:
   void OnDisplayConfigurationChanged() override;
 
   // ShellObserver:
diff --git a/ash/display/cursor_window_controller.cc b/ash/display/cursor_window_controller.cc
index dbab9b4..633652c 100644
--- a/ash/display/cursor_window_controller.cc
+++ b/ash/display/cursor_window_controller.cc
@@ -4,8 +4,8 @@
 
 #include "ash/display/cursor_window_controller.h"
 
-#include "ash/display/display_controller.h"
 #include "ash/display/mirror_window_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/root_window_controller.h"
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
@@ -122,10 +122,10 @@ void CursorWindowController::UpdateContainer() {
     if (display.is_valid())
       SetDisplay(display);
   } else {
-    aura::Window* mirror_window = Shell::GetInstance()->
-        display_controller()->
-        mirror_window_controller()->
-        GetWindow();
+    aura::Window* mirror_window = Shell::GetInstance()
+                                      ->window_tree_host_manager()
+                                      ->mirror_window_controller()
+                                      ->GetWindow();
     if (mirror_window)
       display_ = Shell::GetScreen()->GetPrimaryDisplay();
     SetContainer(mirror_window);
@@ -139,8 +139,9 @@ void CursorWindowController::SetDisplay(const gfx::Display& display) {
     return;
 
   display_ = display;
-  aura::Window* root_window = Shell::GetInstance()->display_controller()->
-      GetRootWindowForDisplayId(display.id());
+  aura::Window* root_window = Shell::GetInstance()
+                                  ->window_tree_host_manager()
+                                  ->GetRootWindowForDisplayId(display.id());
   if (!root_window)
     return;
 
diff --git a/ash/display/cursor_window_controller_unittest.cc b/ash/display/cursor_window_controller_unittest.cc
index 7cea0f4..d822bce 100644
--- a/ash/display/cursor_window_controller_unittest.cc
+++ b/ash/display/cursor_window_controller_unittest.cc
@@ -4,7 +4,7 @@
 
 #include "ash/display/cursor_window_controller.h"
 
-#include "ash/display/display_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/screen_util.h"
 #include "ash/shell.h"
 #include "ash/test/ash_test_base.h"
@@ -43,8 +43,9 @@ class CursorWindowControllerTest : public test::AshTestBase {
   }
 
   void SetCursorCompositionEnabled(bool enabled) {
-    cursor_window_controller_ =
-        Shell::GetInstance()->display_controller()->cursor_window_controller();
+    cursor_window_controller_ = Shell::GetInstance()
+                                    ->window_tree_host_manager()
+                                    ->cursor_window_controller();
     cursor_window_controller_->SetCursorCompositingEnabled(enabled);
   }
 
@@ -63,14 +64,14 @@ TEST_F(CursorWindowControllerTest, MoveToDifferentDisplay) {
 
   UpdateDisplay("200x200,200x200*2/r");
 
-  DisplayController* display_controller =
-      Shell::GetInstance()->display_controller();
-  int64 primary_display_id = display_controller->GetPrimaryDisplayId();
+  WindowTreeHostManager* window_tree_host_manager =
+      Shell::GetInstance()->window_tree_host_manager();
+  int64 primary_display_id = window_tree_host_manager->GetPrimaryDisplayId();
   int64 secondary_display_id = ScreenUtil::GetSecondaryDisplay().id();
   aura::Window* primary_root =
-      display_controller->GetRootWindowForDisplayId(primary_display_id);
+      window_tree_host_manager->GetRootWindowForDisplayId(primary_display_id);
   aura::Window* secondary_root =
-      display_controller->GetRootWindowForDisplayId(secondary_display_id);
+      window_tree_host_manager->GetRootWindowForDisplayId(secondary_display_id);
 
   ui::test::EventGenerator primary_generator(primary_root);
   primary_generator.MoveMouseToInHost(20, 50);
diff --git a/ash/display/display_manager.h b/ash/display/display_manager.h
index 4983f58..bb26bb3 100644
--- a/ash/display/display_manager.h
+++ b/ash/display/display_manager.h
@@ -38,7 +38,6 @@ class Screen;
 
 namespace ash {
 class AcceleratorControllerTest;
-class DisplayController;
 class DisplayLayoutStore;
 class MouseWarpController;
 class ScreenAsh;
diff --git a/ash/display/display_manager_unittest.cc b/ash/display/display_manager_unittest.cc
index a7ec228..59dcef0 100644
--- a/ash/display/display_manager_unittest.cc
+++ b/ash/display/display_manager_unittest.cc
@@ -5,11 +5,11 @@
 #include "ash/display/display_manager.h"
 
 #include "ash/ash_switches.h"
-#include "ash/display/display_controller.h"
 #include "ash/display/display_info.h"
 #include "ash/display/display_layout_store.h"
 #include "ash/display/display_util.h"
 #include "ash/display/mirror_window_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/screen_util.h"
 #include "ash/shell.h"
 #include "ash/test/ash_test_base.h"
@@ -395,7 +395,7 @@ TEST_F(DisplayManagerTest, OverscanInsetsTest) {
             updated_display_info2.GetOverscanInsetsInPixel().ToString());
 
   // Make sure switching primary display applies the overscan offset only once.
-  ash::Shell::GetInstance()->display_controller()->SetPrimaryDisplay(
+  ash::Shell::GetInstance()->window_tree_host_manager()->SetPrimaryDisplay(
       ScreenUtil::GetSecondaryDisplay());
   EXPECT_EQ("-500,0 500x500",
             ScreenUtil::GetSecondaryDisplay().bounds().ToString());
@@ -650,7 +650,7 @@ TEST_F(DisplayManagerTest, DisplayAddRemoveAtTheSameTime) {
 
   UpdateDisplay("100+0-500x500,0+501-400x400");
 
-  const int64 primary_id = DisplayController::GetPrimaryDisplayId();
+  const int64 primary_id = WindowTreeHostManager::GetPrimaryDisplayId();
   const int64 secondary_id = ScreenUtil::GetSecondaryDisplay().id();
 
   DisplayInfo primary_info = display_manager()->GetDisplayInfo(primary_id);
@@ -667,7 +667,7 @@ TEST_F(DisplayManagerTest, DisplayAddRemoveAtTheSameTime) {
   display_info_list.push_back(secondary_info);
   display_manager()->OnNativeDisplaysChanged(display_info_list);
 
-  EXPECT_EQ(third_id, DisplayController::GetPrimaryDisplayId());
+  EXPECT_EQ(third_id, WindowTreeHostManager::GetPrimaryDisplayId());
   EXPECT_EQ("600x600", GetDisplayForId(third_id).size().ToString());
   EXPECT_EQ(secondary_id, ScreenUtil::GetSecondaryDisplay().id());
 }
@@ -722,7 +722,7 @@ TEST_F(DisplayManagerTest, NativeDisplaysChangedAfterPrimaryChange) {
             GetDisplayForId(internal_display_id).bounds().ToString());
   EXPECT_EQ("500,0 100x100", GetDisplayForId(10).bounds().ToString());
 
-  ash::Shell::GetInstance()->display_controller()->SetPrimaryDisplay(
+  ash::Shell::GetInstance()->window_tree_host_manager()->SetPrimaryDisplay(
       GetDisplayForId(secondary_display_info.id()));
   EXPECT_EQ("-500,0 500x500",
             GetDisplayForId(internal_display_id).bounds().ToString());
@@ -1317,14 +1317,16 @@ TEST_F(DisplayManagerTest, SingleDisplayToSoftwareMirroring) {
 
   EXPECT_TRUE(display_manager->IsInMirrorMode());
   EXPECT_EQ(1U, display_manager->GetNumDisplays());
-  DisplayController* display_controller =
-      ash::Shell::GetInstance()->display_controller();
-  EXPECT_TRUE(display_controller->mirror_window_controller()->GetWindow());
+  WindowTreeHostManager* window_tree_host_manager =
+      ash::Shell::GetInstance()->window_tree_host_manager();
+  EXPECT_TRUE(
+      window_tree_host_manager->mirror_window_controller()->GetWindow());
 
   UpdateDisplay("600x400");
   EXPECT_FALSE(display_manager->IsInMirrorMode());
   EXPECT_EQ(1U, display_manager->GetNumDisplays());
-  EXPECT_FALSE(display_controller->mirror_window_controller()->GetWindow());
+  EXPECT_FALSE(
+      window_tree_host_manager->mirror_window_controller()->GetWindow());
 }
 
 #if defined(OS_CHROMEOS)
@@ -1422,7 +1424,7 @@ TEST_F(DisplayManagerTest, NotifyPrimaryChange) {
   if (!SupportsMultipleDisplays())
     return;
   UpdateDisplay("500x500,500x500");
-  ash::Shell::GetInstance()->display_controller()->SwapPrimaryDisplay();
+  ash::Shell::GetInstance()->window_tree_host_manager()->SwapPrimaryDisplay();
   reset();
   UpdateDisplay("500x500");
   EXPECT_FALSE(changed_metrics() & gfx::DisplayObserver::DISPLAY_METRIC_BOUNDS);
@@ -1432,7 +1434,7 @@ TEST_F(DisplayManagerTest, NotifyPrimaryChange) {
               gfx::DisplayObserver::DISPLAY_METRIC_PRIMARY);
 
   UpdateDisplay("500x500,500x500");
-  ash::Shell::GetInstance()->display_controller()->SwapPrimaryDisplay();
+  ash::Shell::GetInstance()->window_tree_host_manager()->SwapPrimaryDisplay();
   reset();
   UpdateDisplay("500x400");
   EXPECT_TRUE(changed_metrics() & gfx::DisplayObserver::DISPLAY_METRIC_BOUNDS);
diff --git a/ash/display/mirror_window_controller.cc b/ash/display/mirror_window_controller.cc
index e971259..06ada9f 100644
--- a/ash/display/mirror_window_controller.cc
+++ b/ash/display/mirror_window_controller.cc
@@ -13,11 +13,11 @@
 #endif
 
 #include "ash/display/cursor_window_controller.h"
-#include "ash/display/display_controller.h"
 #include "ash/display/display_info.h"
 #include "ash/display/display_manager.h"
 #include "ash/display/root_window_transformers.h"
 #include "ash/display/screen_position_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/host/ash_window_tree_host.h"
 #include "ash/host/ash_window_tree_host_init_params.h"
 #include "ash/host/root_window_transformer.h"
@@ -187,14 +187,15 @@ void MirrorWindowController::UpdateWindow(
 
       aura::WindowTreeHost* host = host_info->ash_host->AsWindowTreeHost();
       host->SetSharedInputMethod(
-          Shell::GetInstance()->display_controller()->input_method());
+          Shell::GetInstance()->window_tree_host_manager()->input_method());
       host->window()->SetName(
           base::StringPrintf("MirrorRootWindow-%d", mirror_host_count++));
       host->compositor()->SetBackgroundColor(SK_ColorBLACK);
-      // No need to remove the observer because the DisplayController outlives
+      // No need to remove the observer because the WindowTreeHostManager
+      // outlives
       // the
       // host.
-      host->AddObserver(Shell::GetInstance()->display_controller());
+      host->AddObserver(Shell::GetInstance()->window_tree_host_manager());
       host->AddObserver(this);
       // TODO(oshima): TouchHUD is using idkey.
       InitRootWindowSettings(host->window())->display_id = display_info.id();
@@ -209,7 +210,7 @@ void MirrorWindowController::UpdateWindow(
         host_info->ash_host->ConfineCursorToRootWindow();
         AshWindowTreeHost* unified_ash_host =
             Shell::GetInstance()
-                ->display_controller()
+                ->window_tree_host_manager()
                 ->GetAshWindowTreeHostForDisplayId(
                     Shell::GetScreen()->GetPrimaryDisplay().id());
         unified_ash_host->RegisterMirroringHost(host_info->ash_host.get());
@@ -303,7 +304,7 @@ void MirrorWindowController::OnHostResized(const aura::WindowTreeHost* host) {
       // No need to update the transformer as new transformer is already set
       // in UpdateWindow.
       Shell::GetInstance()
-          ->display_controller()
+          ->window_tree_host_manager()
           ->cursor_window_controller()
           ->UpdateLocation();
       return;
@@ -366,7 +367,7 @@ void MirrorWindowController::CloseAndDeleteHost(MirroringHostInfo* host_info,
   aura::client::SetCaptureClient(host->window(), nullptr);
   delete capture_client;
 
-  host->RemoveObserver(Shell::GetInstance()->display_controller());
+  host->RemoveObserver(Shell::GetInstance()->window_tree_host_manager());
   host->RemoveObserver(this);
   host_info->ash_host->PrepareForShutdown();
   reflector_->RemoveMirroringLayer(host_info->mirror_window->layer());
diff --git a/ash/display/mirror_window_controller_unittest.cc b/ash/display/mirror_window_controller_unittest.cc
index 644d2ed..5c2fb01 100644
--- a/ash/display/mirror_window_controller_unittest.cc
+++ b/ash/display/mirror_window_controller_unittest.cc
@@ -5,8 +5,8 @@
 #include "ash/display/mirror_window_controller.h"
 
 #include "ash/ash_switches.h"
-#include "ash/display/display_controller.h"
 #include "ash/display/display_manager.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/screen_util.h"
 #include "ash/shell.h"
 #include "ash/test/ash_test_base.h"
@@ -217,17 +217,18 @@ TEST_F(MirrorWindowControllerTest, MAYBE_MirrorCursorLocations) {
 TEST_F(MirrorWindowControllerTest, MAYBE_MirrorCursorMoveOnEnter) {
   aura::Env* env = aura::Env::GetInstance();
   Shell* shell = Shell::GetInstance();
-  DisplayController* display_controller = shell->display_controller();
+  WindowTreeHostManager* window_tree_host_manager =
+      shell->window_tree_host_manager();
 
   UpdateDisplay("400x400*2/r,400x400");
-  int64 primary_display_id = display_controller->GetPrimaryDisplayId();
+  int64 primary_display_id = window_tree_host_manager->GetPrimaryDisplayId();
   int64 secondary_display_id = ScreenUtil::GetSecondaryDisplay().id();
   test::ScopedSetInternalDisplayId set_internal(primary_display_id);
 
   // Chrome uses the internal display as the source display for software mirror
   // mode. Move the cursor to the external display.
   aura::Window* secondary_root_window =
-      display_controller->GetRootWindowForDisplayId(secondary_display_id);
+      window_tree_host_manager->GetRootWindowForDisplayId(secondary_display_id);
   secondary_root_window->MoveCursorTo(gfx::Point(100, 200));
   EXPECT_EQ("300,200", env->last_mouse_location().ToString());
   test::CursorManagerTestApi cursor_test_api(shell->cursor_manager());
diff --git a/ash/display/mouse_cursor_event_filter.cc b/ash/display/mouse_cursor_event_filter.cc
index fb24f2c..570058f 100644
--- a/ash/display/mouse_cursor_event_filter.cc
+++ b/ash/display/mouse_cursor_event_filter.cc
@@ -15,11 +15,11 @@
 namespace ash {
 
 MouseCursorEventFilter::MouseCursorEventFilter() : mouse_warp_enabled_(true) {
-  Shell::GetInstance()->display_controller()->AddObserver(this);
+  Shell::GetInstance()->window_tree_host_manager()->AddObserver(this);
 }
 
 MouseCursorEventFilter::~MouseCursorEventFilter() {
-  Shell::GetInstance()->display_controller()->RemoveObserver(this);
+  Shell::GetInstance()->window_tree_host_manager()->RemoveObserver(this);
 }
 
 void MouseCursorEventFilter::ShowSharedEdgeIndicator(aura::Window* from) {
@@ -57,8 +57,10 @@ void MouseCursorEventFilter::OnMouseEvent(ui::MouseEvent* event) {
       return;
   }
 
-  Shell::GetInstance()->display_controller()->
-      cursor_window_controller()->UpdateLocation();
+  Shell::GetInstance()
+      ->window_tree_host_manager()
+      ->cursor_window_controller()
+      ->UpdateLocation();
   mouse_warp_controller_->SetEnabled(mouse_warp_enabled_);
 
   if (mouse_warp_controller_->WarpMouseCursor(event))
diff --git a/ash/display/mouse_cursor_event_filter.h b/ash/display/mouse_cursor_event_filter.h
index 46c1e5a..a6652a5 100644
--- a/ash/display/mouse_cursor_event_filter.h
+++ b/ash/display/mouse_cursor_event_filter.h
@@ -6,7 +6,7 @@
 #define ASH_DISPLAY_MOUSE_CURSOR_EVENT_FILTER_H
 
 #include "ash/ash_export.h"
-#include "ash/display/display_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "base/compiler_specific.h"
 #include "base/gtest_prod_util.h"
 #include "base/memory/scoped_ptr.h"
@@ -23,8 +23,9 @@ class DisplayEdgeController;
 
 // An event filter that controls mouse location in extended desktop
 // environment.
-class ASH_EXPORT MouseCursorEventFilter : public ui::EventHandler,
-                                          public DisplayController::Observer {
+class ASH_EXPORT MouseCursorEventFilter
+    : public ui::EventHandler,
+      public WindowTreeHostManager::Observer {
  public:
   MouseCursorEventFilter();
   ~MouseCursorEventFilter() override;
@@ -36,7 +37,7 @@ class ASH_EXPORT MouseCursorEventFilter : public ui::EventHandler,
   void ShowSharedEdgeIndicator(aura::Window* from);
   void HideSharedEdgeIndicator();
 
-  // DisplayController::Observer:
+  // WindowTreeHostManager::Observer:
   void OnDisplaysInitialized() override;
   void OnDisplayConfigurationChanged() override;
 
diff --git a/ash/display/resolution_notification_controller.cc b/ash/display/resolution_notification_controller.cc
index a0e98ea..b2238c8 100644
--- a/ash/display/resolution_notification_controller.cc
+++ b/ash/display/resolution_notification_controller.cc
@@ -4,7 +4,6 @@
 
 #include "ash/display/resolution_notification_controller.h"
 
-#include "ash/display/display_controller.h"
 #include "ash/display/display_info.h"
 #include "ash/display/display_manager.h"
 #include "ash/shell.h"
@@ -150,12 +149,12 @@ ResolutionNotificationController::ResolutionChangeInfo::
 }
 
 ResolutionNotificationController::ResolutionNotificationController() {
-  Shell::GetInstance()->display_controller()->AddObserver(this);
+  Shell::GetInstance()->window_tree_host_manager()->AddObserver(this);
   Shell::GetScreen()->AddObserver(this);
 }
 
 ResolutionNotificationController::~ResolutionNotificationController() {
-  Shell::GetInstance()->display_controller()->RemoveObserver(this);
+  Shell::GetInstance()->window_tree_host_manager()->RemoveObserver(this);
   Shell::GetScreen()->RemoveObserver(this);
 }
 
diff --git a/ash/display/resolution_notification_controller.h b/ash/display/resolution_notification_controller.h
index 23a1f69..8a74ae8 100644
--- a/ash/display/resolution_notification_controller.h
+++ b/ash/display/resolution_notification_controller.h
@@ -6,7 +6,7 @@
 #define ASH_DISPLAY_RESOLUTION_NOTIFICATION_CONTROLLER_H_
 
 #include "ash/ash_export.h"
-#include "ash/display/display_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "base/callback.h"
 #include "base/gtest_prod_util.h"
 #include "base/timer/timer.h"
@@ -30,7 +30,7 @@ struct DisplayMode;
 // also manages the timeout in case the new resolution is unusable.
 class ASH_EXPORT ResolutionNotificationController
     : public gfx::DisplayObserver,
-      public DisplayController::Observer {
+      public WindowTreeHostManager::Observer {
  public:
   ResolutionNotificationController();
   ~ResolutionNotificationController() override;
@@ -91,7 +91,7 @@ class ASH_EXPORT ResolutionNotificationController
   void OnDisplayMetricsChanged(const gfx::Display& display,
                                uint32_t metrics) override;
 
-  // DisplayController::Observer overrides:
+  // WindowTreeHostManager::Observer overrides:
   void OnDisplayConfigurationChanged() override;
 
   static void SuppressTimerForTest();
diff --git a/ash/display/screen_ash.cc b/ash/display/screen_ash.cc
index 5941bcc..3928e46 100644
--- a/ash/display/screen_ash.cc
+++ b/ash/display/screen_ash.cc
@@ -4,8 +4,8 @@
 
 #include "ash/display/screen_ash.h"
 
-#include "ash/display/display_controller.h"
 #include "ash/display/display_manager.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/root_window_controller.h"
 #include "ash/root_window_settings.h"
 #include "ash/shelf/shelf_layout_manager.h"
@@ -194,7 +194,7 @@ gfx::Display ScreenAsh::GetDisplayMatching(const gfx::Rect& match_rect) const {
 
 gfx::Display ScreenAsh::GetPrimaryDisplay() const {
   return GetDisplayManager()->GetDisplayForId(
-      DisplayController::GetPrimaryDisplayId());
+      WindowTreeHostManager::GetPrimaryDisplayId());
 }
 
 void ScreenAsh::AddObserver(gfx::DisplayObserver* observer) {
diff --git a/ash/display/screen_position_controller.cc b/ash/display/screen_position_controller.cc
index a64fb4b..f3401d7 100644
--- a/ash/display/screen_position_controller.cc
+++ b/ash/display/screen_position_controller.cc
@@ -4,7 +4,7 @@
 
 #include "ash/display/screen_position_controller.h"
 
-#include "ash/display/display_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/root_window_controller.h"
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
@@ -38,8 +38,9 @@ bool ShouldStayInSameRootWindow(const aura::Window* window) {
 // the child windows and transient children of the transient children.
 void MoveAllTransientChildrenToNewRoot(const gfx::Display& display,
                                        aura::Window* window) {
-  aura::Window* dst_root = Shell::GetInstance()->display_controller()->
-      GetRootWindowForDisplayId(display.id());
+  aura::Window* dst_root = Shell::GetInstance()
+                               ->window_tree_host_manager()
+                               ->GetRootWindowForDisplayId(display.id());
   aura::Window::Windows transient_children =
       ::wm::GetTransientChildren(window);
   for (aura::Window::Windows::iterator iter = transient_children.begin();
@@ -166,9 +167,9 @@ void ScreenPositionController::SetBounds(aura::Window* window,
   //    outside of the display.
   if (!::wm::GetTransientParent(window) &&
       !ShouldStayInSameRootWindow(window)) {
-    aura::Window* dst_root =
-        Shell::GetInstance()->display_controller()->GetRootWindowForDisplayId(
-            display.id());
+    aura::Window* dst_root = Shell::GetInstance()
+                                 ->window_tree_host_manager()
+                                 ->GetRootWindowForDisplayId(display.id());
     DCHECK(dst_root);
     aura::Window* dst_container = NULL;
     if (dst_root != window->GetRootWindow()) {
diff --git a/ash/display/unified_mouse_warp_controller.cc b/ash/display/unified_mouse_warp_controller.cc
index 468d4f0..9334d90 100644
--- a/ash/display/unified_mouse_warp_controller.cc
+++ b/ash/display/unified_mouse_warp_controller.cc
@@ -6,10 +6,10 @@
 
 #include <cmath>
 
-#include "ash/display/display_controller.h"
 #include "ash/display/display_manager.h"
 #include "ash/display/display_util.h"
 #include "ash/display/mirror_window_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/host/ash_window_tree_host.h"
 #include "ash/shell.h"
 #include "ui/aura/window.h"
@@ -25,7 +25,7 @@ namespace {
 
 AshWindowTreeHost* GetMirroringAshWindowTreeHostForDisplayId(int64 display_id) {
   return Shell::GetInstance()
-      ->display_controller()
+      ->window_tree_host_manager()
       ->mirror_window_controller()
       ->GetAshWindowTreeHostForDisplayId(display_id);
 }
diff --git a/ash/display/display_controller.cc b/ash/display/window_tree_host_manager.cc
index fcb0dcb..f1e6aaf 100644
--- a/ash/display/display_controller.cc
+++ b/ash/display/window_tree_host_manager.cc
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "ash/display/display_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 
 #include <algorithm>
 #include <cmath>
@@ -133,9 +133,7 @@ void SetDisplayPropertiesOnHost(AshWindowTreeHost* ash_host,
   gfx::AcceleratedWidget xwindow = host->GetAcceleratedWidget();
   ui::SetIntProperty(xwindow, kInternalProp, kCARDINAL, internal);
   ui::SetIntProperty(xwindow, kRotationProp, kCARDINAL, xrandr_rotation);
-  ui::SetIntProperty(xwindow,
-                     kScaleFactorProp,
-                     kCARDINAL,
+  ui::SetIntProperty(xwindow, kScaleFactorProp, kCARDINAL,
                      100 * display.device_scale_factor());
 #elif defined(USE_OZONE)
   // Scale all motion on High-DPI displays.
@@ -248,24 +246,23 @@ class FocusActivationStore {
 ////////////////////////////////////////////////////////////////////////////////
 // DisplayChangeLimiter
 
-DisplayController::DisplayChangeLimiter::DisplayChangeLimiter()
-    : throttle_timeout_(base::Time::Now()) {
-}
+WindowTreeHostManager::DisplayChangeLimiter::DisplayChangeLimiter()
+    : throttle_timeout_(base::Time::Now()) {}
 
-void DisplayController::DisplayChangeLimiter::SetThrottleTimeout(
+void WindowTreeHostManager::DisplayChangeLimiter::SetThrottleTimeout(
     int64 throttle_ms) {
   throttle_timeout_ =
       base::Time::Now() + base::TimeDelta::FromMilliseconds(throttle_ms);
 }
 
-bool DisplayController::DisplayChangeLimiter::IsThrottled() const {
+bool WindowTreeHostManager::DisplayChangeLimiter::IsThrottled() const {
   return base::Time::Now() < throttle_timeout_;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-// DisplayController
+// WindowTreeHostManager
 
-DisplayController::DisplayController()
+WindowTreeHostManager::WindowTreeHostManager()
     : primary_tree_host_for_replace_(nullptr),
       focus_activation_store_(new FocusActivationStore()),
       cursor_window_controller_(new CursorWindowController()),
@@ -281,17 +278,16 @@ DisplayController::DisplayController()
   primary_display_id = gfx::Display::kInvalidDisplayID;
 }
 
-DisplayController::~DisplayController() {
-}
+WindowTreeHostManager::~WindowTreeHostManager() {}
 
-void DisplayController::Start() {
+void WindowTreeHostManager::Start() {
   Shell::GetScreen()->AddObserver(this);
   Shell::GetInstance()->display_manager()->set_delegate(this);
 }
 
-void DisplayController::Shutdown() {
+void WindowTreeHostManager::Shutdown() {
   // Unset the display manager's delegate here because
-  // DisplayManager outlives DisplayController.
+  // DisplayManager outlives WindowTreeHostManager.
   Shell::GetInstance()->display_manager()->set_delegate(nullptr);
 
   cursor_window_controller_.reset();
@@ -303,12 +299,12 @@ void DisplayController::Shutdown() {
 
   // Delete non primary root window controllers first, then
   // delete the primary root window controller.
-  aura::Window::Windows root_windows = DisplayController::GetAllRootWindows();
+  aura::Window::Windows root_windows =
+      WindowTreeHostManager::GetAllRootWindows();
   std::vector<RootWindowController*> to_delete;
   RootWindowController* primary_rwc = nullptr;
   for (aura::Window::Windows::iterator iter = root_windows.begin();
-       iter != root_windows.end();
-       ++iter) {
+       iter != root_windows.end(); ++iter) {
     RootWindowController* rwc = GetRootWindowController(*iter);
     if (GetRootWindowSettings(*iter)->display_id == primary_id)
       primary_rwc = rwc;
@@ -321,7 +317,7 @@ void DisplayController::Shutdown() {
   delete primary_rwc;
 }
 
-void DisplayController::CreatePrimaryHost(
+void WindowTreeHostManager::CreatePrimaryHost(
     const AshWindowTreeHostInitParams& init_params) {
   const gfx::Display& primary_candidate =
       GetDisplayManager()->GetPrimaryDisplayCandidate();
@@ -330,15 +326,15 @@ void DisplayController::CreatePrimaryHost(
   AddWindowTreeHostForDisplay(primary_candidate, init_params);
 }
 
-void DisplayController::InitDisplays() {
+void WindowTreeHostManager::InitHosts() {
   RootWindowController::CreateForPrimaryDisplay(
       window_tree_hosts_[primary_display_id]);
   DisplayManager* display_manager = GetDisplayManager();
   for (size_t i = 0; i < display_manager->GetNumDisplays(); ++i) {
     const gfx::Display& display = display_manager->GetDisplayAt(i);
     if (primary_display_id != display.id()) {
-      AshWindowTreeHost* ash_host = AddWindowTreeHostForDisplay(
-          display, AshWindowTreeHostInitParams());
+      AshWindowTreeHost* ash_host =
+          AddWindowTreeHostForDisplay(display, AshWindowTreeHostInitParams());
       RootWindowController::CreateForSecondaryDisplay(ash_host);
     }
   }
@@ -346,41 +342,40 @@ void DisplayController::InitDisplays() {
   FOR_EACH_OBSERVER(Observer, observers_, OnDisplaysInitialized());
 }
 
-void DisplayController::AddObserver(Observer* observer) {
+void WindowTreeHostManager::AddObserver(Observer* observer) {
   observers_.AddObserver(observer);
 }
 
-void DisplayController::RemoveObserver(Observer* observer) {
+void WindowTreeHostManager::RemoveObserver(Observer* observer) {
   observers_.RemoveObserver(observer);
 }
 
 // static
-int64 DisplayController::GetPrimaryDisplayId() {
+int64 WindowTreeHostManager::GetPrimaryDisplayId() {
   CHECK_NE(gfx::Display::kInvalidDisplayID, primary_display_id);
   return primary_display_id;
 }
 
-aura::Window* DisplayController::GetPrimaryRootWindow() {
+aura::Window* WindowTreeHostManager::GetPrimaryRootWindow() {
   return GetRootWindowForDisplayId(primary_display_id);
 }
 
-aura::Window* DisplayController::GetRootWindowForDisplayId(int64 id) {
+aura::Window* WindowTreeHostManager::GetRootWindowForDisplayId(int64 id) {
   AshWindowTreeHost* host = GetAshWindowTreeHostForDisplayId(id);
   CHECK(host);
   return GetWindow(host);
 }
 
-AshWindowTreeHost* DisplayController::GetAshWindowTreeHostForDisplayId(
+AshWindowTreeHost* WindowTreeHostManager::GetAshWindowTreeHostForDisplayId(
     int64 display_id) {
-  CHECK_EQ(1u, window_tree_hosts_.count(display_id))
-      << "display id = " << display_id;
+  CHECK_EQ(1u, window_tree_hosts_.count(display_id)) << "display id = "
+                                                     << display_id;
   return window_tree_hosts_[display_id];
 }
 
-void DisplayController::CloseChildWindows() {
+void WindowTreeHostManager::CloseChildWindows() {
   for (WindowTreeHostMap::const_iterator it = window_tree_hosts_.begin();
-       it != window_tree_hosts_.end();
-       ++it) {
+       it != window_tree_hosts_.end(); ++it) {
     aura::Window* root_window = GetWindow(it->second);
     RootWindowController* controller = GetRootWindowController(root_window);
     if (controller) {
@@ -394,11 +389,10 @@ void DisplayController::CloseChildWindows() {
   }
 }
 
-aura::Window::Windows DisplayController::GetAllRootWindows() {
+aura::Window::Windows WindowTreeHostManager::GetAllRootWindows() {
   aura::Window::Windows windows;
   for (WindowTreeHostMap::const_iterator it = window_tree_hosts_.begin();
-       it != window_tree_hosts_.end();
-       ++it) {
+       it != window_tree_hosts_.end(); ++it) {
     DCHECK(it->second);
     if (GetRootWindowController(GetWindow(it->second)))
       windows.push_back(GetWindow(it->second));
@@ -406,21 +400,21 @@ aura::Window::Windows DisplayController::GetAllRootWindows() {
   return windows;
 }
 
-gfx::Insets DisplayController::GetOverscanInsets(int64 display_id) const {
+gfx::Insets WindowTreeHostManager::GetOverscanInsets(int64 display_id) const {
   return GetDisplayManager()->GetOverscanInsets(display_id);
 }
 
-void DisplayController::SetOverscanInsets(int64 display_id,
-                                          const gfx::Insets& insets_in_dip) {
+void WindowTreeHostManager::SetOverscanInsets(
+    int64 display_id,
+    const gfx::Insets& insets_in_dip) {
   GetDisplayManager()->SetOverscanInsets(display_id, insets_in_dip);
 }
 
 std::vector<RootWindowController*>
-DisplayController::GetAllRootWindowControllers() {
+WindowTreeHostManager::GetAllRootWindowControllers() {
   std::vector<RootWindowController*> controllers;
   for (WindowTreeHostMap::const_iterator it = window_tree_hosts_.begin();
-       it != window_tree_hosts_.end();
-       ++it) {
+       it != window_tree_hosts_.end(); ++it) {
     RootWindowController* controller =
         GetRootWindowController(GetWindow(it->second));
     if (controller)
@@ -429,13 +423,13 @@ DisplayController::GetAllRootWindowControllers() {
   return controllers;
 }
 
-void DisplayController::ToggleMirrorMode() {
+void WindowTreeHostManager::ToggleMirrorMode() {
   DisplayManager* display_manager = GetDisplayManager();
   if (display_manager->num_connected_displays() <= 1)
     return;
 
   if (limiter_) {
-    if  (limiter_->IsThrottled())
+    if (limiter_->IsThrottled())
       return;
     limiter_->SetThrottleTimeout(kCycleDisplayThrottleTimeoutMs);
   }
@@ -444,14 +438,14 @@ void DisplayController::ToggleMirrorMode() {
   DisplayConfiguratorAnimation* animation =
       shell->display_configurator_animation();
   animation->StartFadeOutAnimation(base::Bind(
-      &DisplayController::SetMirrorModeAfterAnimation,
+      &WindowTreeHostManager::SetMirrorModeAfterAnimation,
       weak_ptr_factory_.GetWeakPtr(), !display_manager->IsInMirrorMode()));
 #endif
 }
 
-void DisplayController::SwapPrimaryDisplay() {
+void WindowTreeHostManager::SwapPrimaryDisplay() {
   if (limiter_) {
-    if  (limiter_->IsThrottled())
+    if (limiter_->IsThrottled())
       return;
     limiter_->SetThrottleTimeout(kSwapDisplayThrottleTimeoutMs);
   }
@@ -461,9 +455,9 @@ void DisplayController::SwapPrimaryDisplay() {
     DisplayConfiguratorAnimation* animation =
         Shell::GetInstance()->display_configurator_animation();
     if (animation) {
-      animation->StartFadeOutAnimation(base::Bind(
-          &DisplayController::OnFadeOutForSwapDisplayFinished,
-          weak_ptr_factory_.GetWeakPtr()));
+      animation->StartFadeOutAnimation(
+          base::Bind(&WindowTreeHostManager::OnFadeOutForSwapDisplayFinished,
+                     weak_ptr_factory_.GetWeakPtr()));
     } else {
       SetPrimaryDisplay(ScreenUtil::GetSecondaryDisplay());
     }
@@ -473,7 +467,7 @@ void DisplayController::SwapPrimaryDisplay() {
   }
 }
 
-void DisplayController::SetPrimaryDisplayId(int64 id) {
+void WindowTreeHostManager::SetPrimaryDisplayId(int64 id) {
   DCHECK_NE(gfx::Display::kInvalidDisplayID, id);
   if (id == gfx::Display::kInvalidDisplayID || primary_display_id == id)
     return;
@@ -483,7 +477,7 @@ void DisplayController::SetPrimaryDisplayId(int64 id) {
     SetPrimaryDisplay(display);
 }
 
-void DisplayController::SetPrimaryDisplay(
+void WindowTreeHostManager::SetPrimaryDisplay(
     const gfx::Display& new_primary_display) {
   DisplayManager* display_manager = GetDisplayManager();
   DCHECK(new_primary_display.is_valid());
@@ -535,16 +529,16 @@ void DisplayController::SetPrimaryDisplay(
 
   // Update the dispay manager with new display info.
   std::vector<DisplayInfo> display_info_list;
-  display_info_list.push_back(display_manager->GetDisplayInfo(
-      primary_display_id));
-  display_info_list.push_back(display_manager->GetDisplayInfo(
-      ScreenUtil::GetSecondaryDisplay().id()));
+  display_info_list.push_back(
+      display_manager->GetDisplayInfo(primary_display_id));
+  display_info_list.push_back(
+      display_manager->GetDisplayInfo(ScreenUtil::GetSecondaryDisplay().id()));
   GetDisplayManager()->set_force_bounds_changed(true);
   GetDisplayManager()->UpdateDisplays(display_info_list);
   GetDisplayManager()->set_force_bounds_changed(false);
 }
 
-void DisplayController::UpdateMouseLocationAfterDisplayChange() {
+void WindowTreeHostManager::UpdateMouseLocationAfterDisplayChange() {
   // If the mouse is currently on a display in native location,
   // use the same native location. Otherwise find the display closest
   // to the current cursor location in screen coordinates.
@@ -630,7 +624,7 @@ void DisplayController::UpdateMouseLocationAfterDisplayChange() {
 #endif
 }
 
-bool DisplayController::UpdateWorkAreaOfDisplayNearestWindow(
+bool WindowTreeHostManager::UpdateWorkAreaOfDisplayNearestWindow(
     const aura::Window* window,
     const gfx::Insets& insets) {
   const aura::Window* root_window = window->GetRootWindow();
@@ -640,7 +634,7 @@ bool DisplayController::UpdateWorkAreaOfDisplayNearestWindow(
   return GetDisplayManager()->UpdateWorkAreaOfDisplay(id, insets);
 }
 
-void DisplayController::OnDisplayAdded(const gfx::Display& display) {
+void WindowTreeHostManager::OnDisplayAdded(const gfx::Display& display) {
 #if defined(OS_CHROMEOS)
   // If we're switching from/to offscreen WTH, we need to
   // create new WTH for primary display instead of reusing.
@@ -715,7 +709,7 @@ void DisplayController::OnDisplayAdded(const gfx::Display& display) {
   }
 }
 
-void DisplayController::DeleteHost(AshWindowTreeHost* host_to_delete) {
+void WindowTreeHostManager::DeleteHost(AshWindowTreeHost* host_to_delete) {
   ClearDisplayPropertiesOnHost(host_to_delete);
   RootWindowController* controller =
       GetRootWindowController(GetWindow(host_to_delete));
@@ -727,7 +721,7 @@ void DisplayController::DeleteHost(AshWindowTreeHost* host_to_delete) {
   base::MessageLoop::current()->DeleteSoon(FROM_HERE, controller);
 }
 
-void DisplayController::OnDisplayRemoved(const gfx::Display& display) {
+void WindowTreeHostManager::OnDisplayRemoved(const gfx::Display& display) {
   AshWindowTreeHost* host_to_delete = window_tree_hosts_[display.id()];
   CHECK(host_to_delete) << display.ToString();
 
@@ -775,8 +769,8 @@ void DisplayController::OnDisplayRemoved(const gfx::Display& display) {
   window_tree_hosts_.erase(display.id());
 }
 
-void DisplayController::OnDisplayMetricsChanged(const gfx::Display& display,
-                                                uint32_t metrics) {
+void WindowTreeHostManager::OnDisplayMetricsChanged(const gfx::Display& display,
+                                                    uint32_t metrics) {
   if (!(metrics & (DISPLAY_METRIC_BOUNDS | DISPLAY_METRIC_ROTATION |
                    DISPLAY_METRIC_DEVICE_SCALE_FACTOR)))
     return;
@@ -788,7 +782,7 @@ void DisplayController::OnDisplayMetricsChanged(const gfx::Display& display,
   SetDisplayPropertiesOnHost(ash_host, display);
 }
 
-void DisplayController::OnHostResized(const aura::WindowTreeHost* host) {
+void WindowTreeHostManager::OnHostResized(const aura::WindowTreeHost* host) {
   gfx::Display display = Shell::GetScreen()->GetDisplayNearestWindow(
       const_cast<aura::Window*>(host->window()));
 
@@ -799,7 +793,7 @@ void DisplayController::OnHostResized(const aura::WindowTreeHost* host) {
   }
 }
 
-void DisplayController::CreateOrUpdateMirroringDisplay(
+void WindowTreeHostManager::CreateOrUpdateMirroringDisplay(
     const DisplayInfoList& info_list) {
   if (GetDisplayManager()->IsInMirrorMode() ||
       GetDisplayManager()->IsInUnifiedMode()) {
@@ -810,7 +804,7 @@ void DisplayController::CreateOrUpdateMirroringDisplay(
   }
 }
 
-void DisplayController::CloseMirroringDisplayIfNotNecessary() {
+void WindowTreeHostManager::CloseMirroringDisplayIfNotNecessary() {
   mirror_window_controller_->CloseIfNotNecessary();
   // If cursor_compositing is enabled for large cursor, the cursor window is
   // always on the desktop display (the visible cursor on the non-desktop
@@ -820,7 +814,7 @@ void DisplayController::CloseMirroringDisplayIfNotNecessary() {
     cursor_window_controller_->UpdateContainer();
 }
 
-void DisplayController::PreDisplayConfigurationChange(bool clear_focus) {
+void WindowTreeHostManager::PreDisplayConfigurationChange(bool clear_focus) {
   FOR_EACH_OBSERVER(Observer, observers_, OnDisplayConfigurationChanging());
   focus_activation_store_->Store(clear_focus);
   gfx::Screen* screen = Shell::GetScreen();
@@ -837,7 +831,7 @@ void DisplayController::PreDisplayConfigurationChange(bool clear_focus) {
   cursor_location_in_native_coords_for_restore_ = point_in_native;
 }
 
-void DisplayController::PostDisplayConfigurationChange() {
+void WindowTreeHostManager::PostDisplayConfigurationChange() {
   if (limiter_)
     limiter_->SetThrottleTimeout(kAfterDisplayChangeThrottleTimeoutMs);
 
@@ -852,12 +846,12 @@ void DisplayController::PostDisplayConfigurationChange() {
         display_manager->default_multi_display_mode() ==
             DisplayManager::UNIFIED);
 
-    if (Shell::GetScreen()->GetNumDisplays() > 1 ) {
+    if (Shell::GetScreen()->GetNumDisplays() > 1) {
       DisplayLayout layout = layout_store->GetRegisteredDisplayLayout(pair);
       int64 primary_id = layout.primary_id;
-      SetPrimaryDisplayId(
-          primary_id == gfx::Display::kInvalidDisplayID ?
-          pair.first : primary_id);
+      SetPrimaryDisplayId(primary_id == gfx::Display::kInvalidDisplayID
+                              ? pair.first
+                              : primary_id);
       // Update the primary_id in case the above call is
       // ignored. Happens when a) default layout's primary id
       // doesn't exist, or b) the primary_id has already been
@@ -870,7 +864,7 @@ void DisplayController::PostDisplayConfigurationChange() {
   UpdateMouseLocationAfterDisplayChange();
 }
 
-bool DisplayController::DispatchKeyEventPostIME(const ui::KeyEvent& event) {
+bool WindowTreeHostManager::DispatchKeyEventPostIME(const ui::KeyEvent& event) {
   // Getting the active root window to dispatch the event. This isn't
   // significant as the event will be sent to the window resolved by
   // aura::client::FocusClient which is FocusController in ash.
@@ -880,7 +874,7 @@ bool DisplayController::DispatchKeyEventPostIME(const ui::KeyEvent& event) {
   return root_window->GetHost()->DispatchKeyEventPostIME(event);
 }
 
-AshWindowTreeHost* DisplayController::AddWindowTreeHostForDisplay(
+AshWindowTreeHost* WindowTreeHostManager::AddWindowTreeHostForDisplay(
     const gfx::Display& display,
     const AshWindowTreeHostInitParams& init_params) {
   static int host_count = 0;
@@ -909,7 +903,7 @@ AshWindowTreeHost* DisplayController::AddWindowTreeHostForDisplay(
       host_count++));
   host->window()->SetTitle(base::UTF8ToUTF16(display_info.name()));
   host->compositor()->SetBackgroundColor(SK_ColorBLACK);
-  // No need to remove our observer observer because the DisplayController
+  // No need to remove our observer observer because the WindowTreeHostManager
   // outlives the host.
   host->AddObserver(this);
   InitRootWindowSettings(host->window())->display_id = display.id();
@@ -925,15 +919,16 @@ AshWindowTreeHost* DisplayController::AddWindowTreeHostForDisplay(
   return ash_host;
 }
 
-void DisplayController::OnFadeOutForSwapDisplayFinished() {
+void WindowTreeHostManager::OnFadeOutForSwapDisplayFinished() {
 #if defined(OS_CHROMEOS)
   SetPrimaryDisplay(ScreenUtil::GetSecondaryDisplay());
-  Shell::GetInstance()->display_configurator_animation()
+  Shell::GetInstance()
+      ->display_configurator_animation()
       ->StartFadeInAnimation();
 #endif
 }
 
-void DisplayController::SetMirrorModeAfterAnimation(bool mirror) {
+void WindowTreeHostManager::SetMirrorModeAfterAnimation(bool mirror) {
   GetDisplayManager()->SetMirrorMode(mirror);
 }
 
diff --git a/ash/display/display_controller.h b/ash/display/window_tree_host_manager.h
index 9ae9944..9829b28 100644
--- a/ash/display/display_controller.h
+++ b/ash/display/window_tree_host_manager.h
@@ -31,7 +31,8 @@ class WindowTreeHost;
 
 namespace base {
 class Value;
-template <typename T> class JSONValueConverter;
+template <typename T>
+class JSONValueConverter;
 }
 
 namespace gfx {
@@ -50,13 +51,15 @@ class InputMethodEventHandler;
 class MirrorWindowController;
 class RootWindowController;
 
-// DisplayController owns and maintains RootWindows for each attached
+// WindowTreeHostManager owns and maintains RootWindows for each attached
 // display, keeping them in sync with display configuration changes.
-class ASH_EXPORT DisplayController : public gfx::DisplayObserver,
-                                     public aura::WindowTreeHostObserver,
-                                     public DisplayManager::Delegate,
-                                     public ui::internal::InputMethodDelegate {
+class ASH_EXPORT WindowTreeHostManager
+    : public gfx::DisplayObserver,
+      public aura::WindowTreeHostObserver,
+      public DisplayManager::Delegate,
+      public ui::internal::InputMethodDelegate {
  public:
+  // TODO(oshima): Consider moving this to gfx::DisplayObserver.
   class ASH_EXPORT Observer {
    public:
     // Invoked only once after all displays are initialized
@@ -69,20 +72,20 @@ class ASH_EXPORT DisplayController : public gfx::DisplayObserver,
 
     // Invoked when the all display configuration changes
     // have been applied.
-    virtual void OnDisplayConfigurationChanged() {};
+    virtual void OnDisplayConfigurationChanged(){};
 
    protected:
     virtual ~Observer() {}
   };
 
-  DisplayController();
-  ~DisplayController() override;
+  WindowTreeHostManager();
+  ~WindowTreeHostManager() override;
 
   void Start();
   void Shutdown();
 
   // Returns primary display's ID.
-  // TODO(oshima): Move this out from DisplayController;
+  // TODO(oshima): Move this out from WindowTreeHostManager;
   static int64 GetPrimaryDisplayId();
 
   CursorWindowController* cursor_window_controller() {
@@ -97,8 +100,8 @@ class ASH_EXPORT DisplayController : public gfx::DisplayObserver,
   // |initial_bounds| in |init_params|.
   void CreatePrimaryHost(const AshWindowTreeHostInitParams& init_params);
 
-  // Initializes all displays.
-  void InitDisplays();
+  // Initializes all WindowTreeHosts.
+  void InitHosts();
 
   // Add/Remove observers.
   void AddObserver(Observer* observer);
@@ -178,8 +181,8 @@ class ASH_EXPORT DisplayController : public gfx::DisplayObserver,
   }
 
  private:
-  FRIEND_TEST_ALL_PREFIXES(DisplayControllerTest, BoundsUpdated);
-  FRIEND_TEST_ALL_PREFIXES(DisplayControllerTest, SecondaryDisplayLayout);
+  FRIEND_TEST_ALL_PREFIXES(WindowTreeHostManagerTest, BoundsUpdated);
+  FRIEND_TEST_ALL_PREFIXES(WindowTreeHostManagerTest, SecondaryDisplayLayout);
   friend class DisplayManager;
   friend class MirrorWindowController;
 
@@ -246,9 +249,9 @@ class ASH_EXPORT DisplayController : public gfx::DisplayObserver,
   // should be moved after a display configuration change.
   int64 cursor_display_id_for_restore_;
 
-  base::WeakPtrFactory<DisplayController> weak_ptr_factory_;
+  base::WeakPtrFactory<WindowTreeHostManager> weak_ptr_factory_;
 
-  DISALLOW_COPY_AND_ASSIGN(DisplayController);
+  DISALLOW_COPY_AND_ASSIGN(WindowTreeHostManager);
 };
 
 }  // namespace ash
diff --git a/ash/display/display_controller_unittest.cc b/ash/display/window_tree_host_manager_unittest.cc
index 9e72799..b04d72e 100644
--- a/ash/display/display_controller_unittest.cc
+++ b/ash/display/window_tree_host_manager_unittest.cc
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "ash/display/display_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 
 #include "ash/ash_switches.h"
 #include "ash/display/display_info.h"
@@ -42,13 +42,11 @@ namespace {
 
 const char kDesktopBackgroundView[] = "DesktopBackgroundView";
 
-template<typename T>
+template <typename T>
 class Resetter {
  public:
-  explicit Resetter(T* value) : value_(*value) {
-    *value = 0;
-  }
-  ~Resetter() { }
+  explicit Resetter(T* value) : value_(*value) { *value = 0; }
+  ~Resetter() {}
   T value() { return value_; }
 
  private:
@@ -56,7 +54,7 @@ class Resetter {
   DISALLOW_COPY_AND_ASSIGN(Resetter);
 };
 
-class TestObserver : public DisplayController::Observer,
+class TestObserver : public WindowTreeHostManager::Observer,
                      public gfx::DisplayObserver,
                      public aura::client::FocusChangeObserver,
                      public aura::client::ActivationChangeObserver {
@@ -71,24 +69,24 @@ class TestObserver : public DisplayController::Observer,
         changed_display_id_(0),
         focus_changed_count_(0),
         activation_changed_count_(0) {
-    Shell::GetInstance()->display_controller()->AddObserver(this);
+    Shell::GetInstance()->window_tree_host_manager()->AddObserver(this);
     Shell::GetScreen()->AddObserver(this);
-    aura::client::GetFocusClient(Shell::GetPrimaryRootWindow())->
-        AddObserver(this);
-    aura::client::GetActivationClient(Shell::GetPrimaryRootWindow())->
-        AddObserver(this);
+    aura::client::GetFocusClient(Shell::GetPrimaryRootWindow())
+        ->AddObserver(this);
+    aura::client::GetActivationClient(Shell::GetPrimaryRootWindow())
+        ->AddObserver(this);
   }
 
   ~TestObserver() override {
-    Shell::GetInstance()->display_controller()->RemoveObserver(this);
+    Shell::GetInstance()->window_tree_host_manager()->RemoveObserver(this);
     Shell::GetScreen()->RemoveObserver(this);
-    aura::client::GetFocusClient(Shell::GetPrimaryRootWindow())->
-        RemoveObserver(this);
-    aura::client::GetActivationClient(Shell::GetPrimaryRootWindow())->
-        RemoveObserver(this);
+    aura::client::GetFocusClient(Shell::GetPrimaryRootWindow())
+        ->RemoveObserver(this);
+    aura::client::GetActivationClient(Shell::GetPrimaryRootWindow())
+        ->RemoveObserver(this);
   }
 
-  // Overridden from DisplayController::Observer
+  // Overridden from WindowTreeHostManager::Observer
   void OnDisplayConfigurationChanging() override { ++changing_count_; }
   void OnDisplayConfigurationChanged() override { ++changed_count_; }
 
@@ -188,8 +186,7 @@ void SetSecondaryDisplayLayoutAndOffset(DisplayLayout::Position position,
                                         int offset) {
   DisplayLayout layout(position, offset);
   ASSERT_GT(Shell::GetScreen()->GetNumDisplays(), 1);
-  Shell::GetInstance()->display_manager()->
-      SetLayoutForCurrentDisplays(layout);
+  Shell::GetInstance()->display_manager()->SetLayoutForCurrentDisplays(layout);
 }
 
 void SetSecondaryDisplayLayout(DisplayLayout::Position position) {
@@ -197,14 +194,16 @@ void SetSecondaryDisplayLayout(DisplayLayout::Position position) {
 }
 
 void SetDefaultDisplayLayout(DisplayLayout::Position position) {
-  Shell::GetInstance()->display_manager()->layout_store()->
-      SetDefaultDisplayLayout(DisplayLayout(position, 0));
+  Shell::GetInstance()
+      ->display_manager()
+      ->layout_store()
+      ->SetDefaultDisplayLayout(DisplayLayout(position, 0));
 }
 
-class DisplayControllerShutdownTest : public test::AshTestBase {
+class WindowTreeHostManagerShutdownTest : public test::AshTestBase {
  public:
-  DisplayControllerShutdownTest() {}
-  ~DisplayControllerShutdownTest() override {}
+  WindowTreeHostManagerShutdownTest() {}
+  ~WindowTreeHostManagerShutdownTest() override {}
 
   void TearDown() override {
     test::AshTestBase::TearDown();
@@ -218,29 +217,27 @@ class DisplayControllerShutdownTest : public test::AshTestBase {
   }
 
  private:
-  DISALLOW_COPY_AND_ASSIGN(DisplayControllerShutdownTest);
+  DISALLOW_COPY_AND_ASSIGN(WindowTreeHostManagerShutdownTest);
 };
 
 class StartupHelper : public test::TestShellDelegate,
-                      public DisplayController::Observer {
+                      public WindowTreeHostManager::Observer {
  public:
   StartupHelper() : displays_initialized_(false) {}
   ~StartupHelper() override {}
 
   // ash::ShellSelegate:
   void PreInit() override {
-    Shell::GetInstance()->display_controller()->AddObserver(this);
+    Shell::GetInstance()->window_tree_host_manager()->AddObserver(this);
   }
 
-  // ash::DisplayController::Observer:
+  // ash::WindowTreeHostManager::Observer:
   void OnDisplaysInitialized() override {
     DCHECK(!displays_initialized_);
     displays_initialized_ = true;
   }
 
-  bool displays_initialized() const {
-    return displays_initialized_;
-  }
+  bool displays_initialized() const { return displays_initialized_; }
 
  private:
   bool displays_initialized_;
@@ -248,10 +245,10 @@ class StartupHelper : public test::TestShellDelegate,
   DISALLOW_COPY_AND_ASSIGN(StartupHelper);
 };
 
-class DisplayControllerStartupTest : public test::AshTestBase {
+class WindowTreeHostManagerStartupTest : public test::AshTestBase {
  public:
-  DisplayControllerStartupTest() : startup_helper_(new StartupHelper) {}
-  ~DisplayControllerStartupTest() override {}
+  WindowTreeHostManagerStartupTest() : startup_helper_(new StartupHelper) {}
+  ~WindowTreeHostManagerStartupTest() override {}
 
   // ash::test::AshTestBase:
   void SetUp() override {
@@ -259,7 +256,8 @@ class DisplayControllerStartupTest : public test::AshTestBase {
     test::AshTestBase::SetUp();
   }
   void TearDown() override {
-    Shell::GetInstance()->display_controller()->RemoveObserver(startup_helper_);
+    Shell::GetInstance()->window_tree_host_manager()->RemoveObserver(
+        startup_helper_);
     test::AshTestBase::TearDown();
   }
 
@@ -268,18 +266,19 @@ class DisplayControllerStartupTest : public test::AshTestBase {
  private:
   StartupHelper* startup_helper_;  // Owned by ash::Shell.
 
-  DISALLOW_COPY_AND_ASSIGN(DisplayControllerStartupTest);
+  DISALLOW_COPY_AND_ASSIGN(WindowTreeHostManagerStartupTest);
 };
 
 class TestEventHandler : public ui::EventHandler {
  public:
-  TestEventHandler() : target_root_(NULL),
-                       touch_radius_x_(0.0),
-                       touch_radius_y_(0.0),
-                       scroll_x_offset_(0.0),
-                       scroll_y_offset_(0.0),
-                       scroll_x_offset_ordinal_(0.0),
-                       scroll_y_offset_ordinal_(0.0) {}
+  TestEventHandler()
+      : target_root_(NULL),
+        touch_radius_x_(0.0),
+        touch_radius_y_(0.0),
+        scroll_x_offset_(0.0),
+        scroll_y_offset_(0.0),
+        scroll_x_offset_ordinal_(0.0),
+        scroll_y_offset_ordinal_(0.0) {}
   ~TestEventHandler() override {}
 
   void OnMouseEvent(ui::MouseEvent* event) override {
@@ -350,8 +349,10 @@ class TestEventHandler : public ui::EventHandler {
 };
 
 float GetStoredUIScale(int64 id) {
-  return Shell::GetInstance()->display_manager()->GetDisplayInfo(id).
-      GetEffectiveUIScale();
+  return Shell::GetInstance()
+      ->display_manager()
+      ->GetDisplayInfo(id)
+      .GetEffectiveUIScale();
 }
 
 class TestMouseWatcherListener : public views::MouseWatcherListener {
@@ -367,23 +368,23 @@ class TestMouseWatcherListener : public views::MouseWatcherListener {
 
 }  // namespace
 
-typedef test::AshTestBase DisplayControllerTest;
+typedef test::AshTestBase WindowTreeHostManagerTest;
 
-TEST_F(DisplayControllerShutdownTest, Shutdown) {
+TEST_F(WindowTreeHostManagerShutdownTest, Shutdown) {
   if (!SupportsMultipleDisplays())
     return;
 
   UpdateDisplay("444x333, 200x200");
 }
 
-TEST_F(DisplayControllerStartupTest, Startup) {
+TEST_F(WindowTreeHostManagerStartupTest, Startup) {
   if (!SupportsMultipleDisplays())
     return;
 
   EXPECT_TRUE(startup_helper()->displays_initialized());
 }
 
-TEST_F(DisplayControllerTest, SecondaryDisplayLayout) {
+TEST_F(WindowTreeHostManagerTest, SecondaryDisplayLayout) {
   if (!SupportsMultipleDisplays())
     return;
 
@@ -537,8 +538,7 @@ DisplayInfo CreateDisplayInfo(int64 id,
   return info;
 }
 
-DisplayInfo CreateMirroredDisplayInfo(int64 id,
-                                      float device_scale_factor) {
+DisplayInfo CreateMirroredDisplayInfo(int64 id, float device_scale_factor) {
   DisplayInfo info = CreateDisplayInfo(id, 0, gfx::Display::ROTATE_0);
   info.set_device_scale_factor(device_scale_factor);
   return info;
@@ -546,7 +546,7 @@ DisplayInfo CreateMirroredDisplayInfo(int64 id,
 
 }  // namespace
 
-TEST_F(DisplayControllerTest, MirrorToDockedWithFullscreen) {
+TEST_F(WindowTreeHostManagerTest, MirrorToDockedWithFullscreen) {
   if (!SupportsMultipleDisplays())
     return;
 
@@ -557,10 +557,8 @@ TEST_F(DisplayControllerTest, MirrorToDockedWithFullscreen) {
   // Docked mode.
   DisplayManager* display_manager = Shell::GetInstance()->display_manager();
 
-  const DisplayInfo internal_display_info =
-      CreateMirroredDisplayInfo(1, 2.0f);
-  const DisplayInfo external_display_info =
-      CreateMirroredDisplayInfo(2, 1.0f);
+  const DisplayInfo internal_display_info = CreateMirroredDisplayInfo(1, 2.0f);
+  const DisplayInfo external_display_info = CreateMirroredDisplayInfo(2, 1.0f);
 
   std::vector<DisplayInfo> display_info_list;
   // Mirror.
@@ -598,7 +596,7 @@ TEST_F(DisplayControllerTest, MirrorToDockedWithFullscreen) {
   EXPECT_EQ("0,0 500x500", w1->bounds().ToString());
 }
 
-TEST_F(DisplayControllerTest, BoundsUpdated) {
+TEST_F(WindowTreeHostManagerTest, BoundsUpdated) {
   if (!SupportsMultipleDisplays())
     return;
 
@@ -696,12 +694,12 @@ TEST_F(DisplayControllerTest, BoundsUpdated) {
   EXPECT_EQ(0, observer.GetActivationChangedCountAndReset());
 }
 
-TEST_F(DisplayControllerTest, SwapPrimary) {
+TEST_F(WindowTreeHostManagerTest, SwapPrimary) {
   if (!SupportsMultipleDisplays())
     return;
 
-  DisplayController* display_controller =
-      Shell::GetInstance()->display_controller();
+  WindowTreeHostManager* window_tree_host_manager =
+      Shell::GetInstance()->window_tree_host_manager();
   DisplayManager* display_manager = Shell::GetInstance()->display_manager();
 
   UpdateDisplay("200x200,300x300");
@@ -713,17 +711,18 @@ TEST_F(DisplayControllerTest, SwapPrimary) {
 
   EXPECT_NE(primary_display.id(), secondary_display.id());
   aura::Window* primary_root =
-      display_controller->GetRootWindowForDisplayId(primary_display.id());
+      window_tree_host_manager->GetRootWindowForDisplayId(primary_display.id());
   aura::Window* secondary_root =
-      display_controller->GetRootWindowForDisplayId(secondary_display.id());
+      window_tree_host_manager->GetRootWindowForDisplayId(
+          secondary_display.id());
   EXPECT_NE(primary_root, secondary_root);
   aura::Window* shelf_window =
       Shelf::ForPrimaryDisplay()->shelf_widget()->GetNativeView();
   EXPECT_TRUE(primary_root->Contains(shelf_window));
   EXPECT_FALSE(secondary_root->Contains(shelf_window));
-  EXPECT_EQ(primary_display.id(),
-            Shell::GetScreen()->GetDisplayNearestPoint(
-                gfx::Point(-100, -100)).id());
+  EXPECT_EQ(
+      primary_display.id(),
+      Shell::GetScreen()->GetDisplayNearestPoint(gfx::Point(-100, -100)).id());
   EXPECT_EQ(primary_display.id(),
             Shell::GetScreen()->GetDisplayNearestWindow(NULL).id());
 
@@ -731,11 +730,10 @@ TEST_F(DisplayControllerTest, SwapPrimary) {
   EXPECT_EQ("0,0 200x153", primary_display.work_area().ToString());
   EXPECT_EQ("200,0 300x300", secondary_display.bounds().ToString());
   EXPECT_EQ("200,0 300x253", secondary_display.work_area().ToString());
-  EXPECT_EQ("right, 50",
-            display_manager->GetCurrentDisplayLayout().ToString());
+  EXPECT_EQ("right, 50", display_manager->GetCurrentDisplayLayout().ToString());
 
   // Switch primary and secondary
-  display_controller->SetPrimaryDisplay(secondary_display);
+  window_tree_host_manager->SetPrimaryDisplay(secondary_display);
   const DisplayLayout& inverted_layout =
       display_manager->GetCurrentDisplayLayout();
   EXPECT_EQ("left, -50", inverted_layout.ToString());
@@ -743,18 +741,16 @@ TEST_F(DisplayControllerTest, SwapPrimary) {
   EXPECT_EQ(secondary_display.id(),
             Shell::GetScreen()->GetPrimaryDisplay().id());
   EXPECT_EQ(primary_display.id(), ScreenUtil::GetSecondaryDisplay().id());
-  EXPECT_EQ(primary_display.id(),
-            Shell::GetScreen()->GetDisplayNearestPoint(
-                gfx::Point(-100, -100)).id());
+  EXPECT_EQ(
+      primary_display.id(),
+      Shell::GetScreen()->GetDisplayNearestPoint(gfx::Point(-100, -100)).id());
   EXPECT_EQ(secondary_display.id(),
             Shell::GetScreen()->GetDisplayNearestWindow(NULL).id());
 
-  EXPECT_EQ(
-      primary_root,
-      display_controller->GetRootWindowForDisplayId(secondary_display.id()));
-  EXPECT_EQ(
-      secondary_root,
-      display_controller->GetRootWindowForDisplayId(primary_display.id()));
+  EXPECT_EQ(primary_root, window_tree_host_manager->GetRootWindowForDisplayId(
+                              secondary_display.id()));
+  EXPECT_EQ(secondary_root, window_tree_host_manager->GetRootWindowForDisplayId(
+                                primary_display.id()));
   EXPECT_TRUE(primary_root->Contains(shelf_window));
   EXPECT_FALSE(secondary_root->Contains(shelf_window));
 
@@ -776,9 +772,9 @@ TEST_F(DisplayControllerTest, SwapPrimary) {
   RunAllPendingInMessageLoop();  // RootWindow is deleted in a posted task.
   EXPECT_EQ(1, Shell::GetScreen()->GetNumDisplays());
   EXPECT_EQ(primary_display.id(), Shell::GetScreen()->GetPrimaryDisplay().id());
-  EXPECT_EQ(primary_display.id(),
-            Shell::GetScreen()->GetDisplayNearestPoint(
-                gfx::Point(-100, -100)).id());
+  EXPECT_EQ(
+      primary_display.id(),
+      Shell::GetScreen()->GetDisplayNearestPoint(gfx::Point(-100, -100)).id());
   EXPECT_EQ(primary_display.id(),
             Shell::GetScreen()->GetDisplayNearestWindow(NULL).id());
   EXPECT_TRUE(tracker.Contains(primary_root));
@@ -786,12 +782,12 @@ TEST_F(DisplayControllerTest, SwapPrimary) {
   EXPECT_TRUE(primary_root->Contains(shelf_window));
 }
 
-TEST_F(DisplayControllerTest, FindNearestDisplay) {
+TEST_F(WindowTreeHostManagerTest, FindNearestDisplay) {
   if (!SupportsMultipleDisplays())
     return;
 
-  DisplayController* display_controller =
-      Shell::GetInstance()->display_controller();
+  WindowTreeHostManager* window_tree_host_manager =
+      Shell::GetInstance()->window_tree_host_manager();
   DisplayManager* display_manager = Shell::GetInstance()->display_manager();
 
   UpdateDisplay("200x200,300x300");
@@ -802,38 +798,48 @@ TEST_F(DisplayControllerTest, FindNearestDisplay) {
   gfx::Display secondary_display = ScreenUtil::GetSecondaryDisplay();
   EXPECT_NE(primary_display.id(), secondary_display.id());
   aura::Window* primary_root =
-      display_controller->GetRootWindowForDisplayId(primary_display.id());
+      window_tree_host_manager->GetRootWindowForDisplayId(primary_display.id());
   aura::Window* secondary_root =
-      display_controller->GetRootWindowForDisplayId(secondary_display.id());
+      window_tree_host_manager->GetRootWindowForDisplayId(
+          secondary_display.id());
   EXPECT_NE(primary_root, secondary_root);
 
   // Test that points outside of any display return the nearest display.
-  EXPECT_EQ(primary_display.id(), Shell::GetScreen()->GetDisplayNearestPoint(
-      gfx::Point(-100, 0)).id());
-  EXPECT_EQ(primary_display.id(), Shell::GetScreen()->GetDisplayNearestPoint(
-      gfx::Point(0, -100)).id());
-  EXPECT_EQ(primary_display.id(), Shell::GetScreen()->GetDisplayNearestPoint(
-      gfx::Point(100, 100)).id());
-  EXPECT_EQ(primary_display.id(), Shell::GetScreen()->GetDisplayNearestPoint(
-      gfx::Point(224, 25)).id());
-  EXPECT_EQ(secondary_display.id(), Shell::GetScreen()->GetDisplayNearestPoint(
-      gfx::Point(226, 25)).id());
-  EXPECT_EQ(secondary_display.id(), Shell::GetScreen()->GetDisplayNearestPoint(
-      gfx::Point(600, 100)).id());
-  EXPECT_EQ(primary_display.id(), Shell::GetScreen()->GetDisplayNearestPoint(
-      gfx::Point(174, 225)).id());
-  EXPECT_EQ(secondary_display.id(), Shell::GetScreen()->GetDisplayNearestPoint(
-      gfx::Point(176, 225)).id());
-  EXPECT_EQ(secondary_display.id(), Shell::GetScreen()->GetDisplayNearestPoint(
-      gfx::Point(300, 400)).id());
+  EXPECT_EQ(
+      primary_display.id(),
+      Shell::GetScreen()->GetDisplayNearestPoint(gfx::Point(-100, 0)).id());
+  EXPECT_EQ(
+      primary_display.id(),
+      Shell::GetScreen()->GetDisplayNearestPoint(gfx::Point(0, -100)).id());
+  EXPECT_EQ(
+      primary_display.id(),
+      Shell::GetScreen()->GetDisplayNearestPoint(gfx::Point(100, 100)).id());
+  EXPECT_EQ(
+      primary_display.id(),
+      Shell::GetScreen()->GetDisplayNearestPoint(gfx::Point(224, 25)).id());
+  EXPECT_EQ(
+      secondary_display.id(),
+      Shell::GetScreen()->GetDisplayNearestPoint(gfx::Point(226, 25)).id());
+  EXPECT_EQ(
+      secondary_display.id(),
+      Shell::GetScreen()->GetDisplayNearestPoint(gfx::Point(600, 100)).id());
+  EXPECT_EQ(
+      primary_display.id(),
+      Shell::GetScreen()->GetDisplayNearestPoint(gfx::Point(174, 225)).id());
+  EXPECT_EQ(
+      secondary_display.id(),
+      Shell::GetScreen()->GetDisplayNearestPoint(gfx::Point(176, 225)).id());
+  EXPECT_EQ(
+      secondary_display.id(),
+      Shell::GetScreen()->GetDisplayNearestPoint(gfx::Point(300, 400)).id());
 }
 
-TEST_F(DisplayControllerTest, SwapPrimaryById) {
+TEST_F(WindowTreeHostManagerTest, SwapPrimaryById) {
   if (!SupportsMultipleDisplays())
     return;
 
-  DisplayController* display_controller =
-      Shell::GetInstance()->display_controller();
+  WindowTreeHostManager* window_tree_host_manager =
+      Shell::GetInstance()->window_tree_host_manager();
   DisplayManager* display_manager = Shell::GetInstance()->display_manager();
 
   UpdateDisplay("200x200,300x300");
@@ -845,34 +851,33 @@ TEST_F(DisplayControllerTest, SwapPrimaryById) {
 
   EXPECT_NE(primary_display.id(), secondary_display.id());
   aura::Window* primary_root =
-      display_controller->GetRootWindowForDisplayId(primary_display.id());
+      window_tree_host_manager->GetRootWindowForDisplayId(primary_display.id());
   aura::Window* secondary_root =
-      display_controller->GetRootWindowForDisplayId(secondary_display.id());
+      window_tree_host_manager->GetRootWindowForDisplayId(
+          secondary_display.id());
   aura::Window* shelf_window =
       Shelf::ForPrimaryDisplay()->shelf_widget()->GetNativeView();
   EXPECT_TRUE(primary_root->Contains(shelf_window));
   EXPECT_FALSE(secondary_root->Contains(shelf_window));
   EXPECT_NE(primary_root, secondary_root);
-  EXPECT_EQ(primary_display.id(),
-            Shell::GetScreen()->GetDisplayNearestPoint(
-                gfx::Point(-100, -100)).id());
+  EXPECT_EQ(
+      primary_display.id(),
+      Shell::GetScreen()->GetDisplayNearestPoint(gfx::Point(-100, -100)).id());
   EXPECT_EQ(primary_display.id(),
             Shell::GetScreen()->GetDisplayNearestWindow(NULL).id());
 
   // Switch primary and secondary by display ID.
   TestObserver observer;
-  display_controller->SetPrimaryDisplayId(secondary_display.id());
+  window_tree_host_manager->SetPrimaryDisplayId(secondary_display.id());
   EXPECT_EQ(secondary_display.id(),
             Shell::GetScreen()->GetPrimaryDisplay().id());
   EXPECT_EQ(primary_display.id(), ScreenUtil::GetSecondaryDisplay().id());
   EXPECT_LT(0, observer.CountAndReset());
 
-  EXPECT_EQ(
-      primary_root,
-      display_controller->GetRootWindowForDisplayId(secondary_display.id()));
-  EXPECT_EQ(
-      secondary_root,
-      display_controller->GetRootWindowForDisplayId(primary_display.id()));
+  EXPECT_EQ(primary_root, window_tree_host_manager->GetRootWindowForDisplayId(
+                              secondary_display.id()));
+  EXPECT_EQ(secondary_root, window_tree_host_manager->GetRootWindowForDisplayId(
+                                primary_display.id()));
   EXPECT_TRUE(primary_root->Contains(shelf_window));
   EXPECT_FALSE(secondary_root->Contains(shelf_window));
 
@@ -882,7 +887,7 @@ TEST_F(DisplayControllerTest, SwapPrimaryById) {
   EXPECT_EQ("left, -50", inverted_layout.ToString());
 
   // Calling the same ID don't do anything.
-  display_controller->SetPrimaryDisplayId(secondary_display.id());
+  window_tree_host_manager->SetPrimaryDisplayId(secondary_display.id());
   EXPECT_EQ(0, observer.CountAndReset());
 
   aura::WindowTracker tracker;
@@ -894,9 +899,9 @@ TEST_F(DisplayControllerTest, SwapPrimaryById) {
   RunAllPendingInMessageLoop();  // RootWindow is deleted in a posted task.
   EXPECT_EQ(1, Shell::GetScreen()->GetNumDisplays());
   EXPECT_EQ(primary_display.id(), Shell::GetScreen()->GetPrimaryDisplay().id());
-  EXPECT_EQ(primary_display.id(),
-            Shell::GetScreen()->GetDisplayNearestPoint(
-                gfx::Point(-100, -100)).id());
+  EXPECT_EQ(
+      primary_display.id(),
+      Shell::GetScreen()->GetDisplayNearestPoint(gfx::Point(-100, -100)).id());
   EXPECT_EQ(primary_display.id(),
             Shell::GetScreen()->GetDisplayNearestWindow(NULL).id());
   EXPECT_TRUE(tracker.Contains(primary_root));
@@ -916,19 +921,17 @@ TEST_F(DisplayControllerTest, SwapPrimaryById) {
   EXPECT_EQ(secondary_display.id(),
             Shell::GetScreen()->GetPrimaryDisplay().id());
   EXPECT_EQ(primary_display.id(), ScreenUtil::GetSecondaryDisplay().id());
-  EXPECT_EQ(
-      primary_root,
-      display_controller->GetRootWindowForDisplayId(secondary_display.id()));
-  EXPECT_NE(
-      primary_root,
-      display_controller->GetRootWindowForDisplayId(primary_display.id()));
+  EXPECT_EQ(primary_root, window_tree_host_manager->GetRootWindowForDisplayId(
+                              secondary_display.id()));
+  EXPECT_NE(primary_root, window_tree_host_manager->GetRootWindowForDisplayId(
+                              primary_display.id()));
   EXPECT_TRUE(primary_root->Contains(shelf_window));
 
   // Deleting 2nd display and adding 2nd display with a different ID.  The 2nd
   // display shouldn't become primary.
   UpdateDisplay("200x200");
-  DisplayInfo third_display_info(
-      secondary_display.id() + 1, std::string(), false);
+  DisplayInfo third_display_info(secondary_display.id() + 1, std::string(),
+                                 false);
   third_display_info.SetBounds(secondary_display.bounds());
   ASSERT_NE(primary_display.id(), third_display_info.id());
 
@@ -939,24 +942,21 @@ TEST_F(DisplayControllerTest, SwapPrimaryById) {
   display_info_list2.push_back(third_display_info);
   display_manager->OnNativeDisplaysChanged(display_info_list2);
   EXPECT_EQ(2, Shell::GetScreen()->GetNumDisplays());
-  EXPECT_EQ(primary_display.id(),
-            Shell::GetScreen()->GetPrimaryDisplay().id());
+  EXPECT_EQ(primary_display.id(), Shell::GetScreen()->GetPrimaryDisplay().id());
   EXPECT_EQ(third_display_info.id(), ScreenUtil::GetSecondaryDisplay().id());
-  EXPECT_EQ(
-      primary_root,
-      display_controller->GetRootWindowForDisplayId(primary_display.id()));
-  EXPECT_NE(
-      primary_root,
-      display_controller->GetRootWindowForDisplayId(third_display_info.id()));
+  EXPECT_EQ(primary_root, window_tree_host_manager->GetRootWindowForDisplayId(
+                              primary_display.id()));
+  EXPECT_NE(primary_root, window_tree_host_manager->GetRootWindowForDisplayId(
+                              third_display_info.id()));
   EXPECT_TRUE(primary_root->Contains(shelf_window));
 }
 
-TEST_F(DisplayControllerTest, OverscanInsets) {
+TEST_F(WindowTreeHostManagerTest, OverscanInsets) {
   if (!SupportsMultipleDisplays())
     return;
 
-  DisplayController* display_controller =
-      Shell::GetInstance()->display_controller();
+  WindowTreeHostManager* window_tree_host_manager =
+      Shell::GetInstance()->window_tree_host_manager();
   TestEventHandler event_handler;
   Shell::GetInstance()->AddPreTargetHandler(&event_handler);
 
@@ -964,8 +964,8 @@ TEST_F(DisplayControllerTest, OverscanInsets) {
   gfx::Display display1 = Shell::GetScreen()->GetPrimaryDisplay();
   aura::Window::Windows root_windows = Shell::GetAllRootWindows();
 
-  display_controller->SetOverscanInsets(display1.id(),
-                                        gfx::Insets(10, 15, 20, 25));
+  window_tree_host_manager->SetOverscanInsets(display1.id(),
+                                              gfx::Insets(10, 15, 20, 25));
   EXPECT_EQ("0,0 80x170", root_windows[0]->bounds().ToString());
   EXPECT_EQ("150x200", root_windows[1]->bounds().size().ToString());
   EXPECT_EQ("80,0 150x200",
@@ -975,7 +975,7 @@ TEST_F(DisplayControllerTest, OverscanInsets) {
   generator.MoveMouseToInHost(20, 25);
   EXPECT_EQ("5,15", event_handler.GetLocationAndReset());
 
-  display_controller->SetOverscanInsets(display1.id(), gfx::Insets());
+  window_tree_host_manager->SetOverscanInsets(display1.id(), gfx::Insets());
   EXPECT_EQ("0,0 120x200", root_windows[0]->bounds().ToString());
   EXPECT_EQ("120,0 150x200",
             ScreenUtil::GetSecondaryDisplay().bounds().ToString());
@@ -988,20 +988,20 @@ TEST_F(DisplayControllerTest, OverscanInsets) {
   UpdateDisplay("400x300*2,600x400/o");
   root_windows = Shell::GetAllRootWindows();
   gfx::Point point;
-  Shell::GetAllRootWindows()[1]->GetHost()->
-      GetRootTransform().TransformPoint(&point);
+  Shell::GetAllRootWindows()[1]->GetHost()->GetRootTransform().TransformPoint(
+      &point);
   EXPECT_EQ("15,10", point.ToString());
 
-  display_controller->SwapPrimaryDisplay();
+  window_tree_host_manager->SwapPrimaryDisplay();
   point.SetPoint(0, 0);
-  Shell::GetAllRootWindows()[1]->GetHost()->
-      GetRootTransform().TransformPoint(&point);
+  Shell::GetAllRootWindows()[1]->GetHost()->GetRootTransform().TransformPoint(
+      &point);
   EXPECT_EQ("15,10", point.ToString());
 
   Shell::GetInstance()->RemovePreTargetHandler(&event_handler);
 }
 
-TEST_F(DisplayControllerTest, Rotate) {
+TEST_F(WindowTreeHostManagerTest, Rotate) {
   if (!SupportsMultipleDisplays())
     return;
 
@@ -1076,7 +1076,7 @@ TEST_F(DisplayControllerTest, Rotate) {
   Shell::GetInstance()->RemovePreTargetHandler(&event_handler);
 }
 
-TEST_F(DisplayControllerTest, ScaleRootWindow) {
+TEST_F(WindowTreeHostManagerTest, ScaleRootWindow) {
   if (!SupportsMultipleDisplays())
     return;
 
@@ -1112,7 +1112,7 @@ TEST_F(DisplayControllerTest, ScaleRootWindow) {
   Shell::GetInstance()->RemovePreTargetHandler(&event_handler);
 }
 
-TEST_F(DisplayControllerTest, TouchScale) {
+TEST_F(WindowTreeHostManagerTest, TouchScale) {
   if (!SupportsMultipleDisplays())
     return;
 
@@ -1131,9 +1131,9 @@ TEST_F(DisplayControllerTest, TouchScale) {
   EXPECT_EQ(0.5, event_handler.touch_radius_x());
   EXPECT_EQ(0.5, event_handler.touch_radius_y());
 
-  generator.ScrollSequence(gfx::Point(0,0),
-                           base::TimeDelta::FromMilliseconds(100),
-                           10.0, 1.0, 5, 1);
+  generator.ScrollSequence(gfx::Point(0, 0),
+                           base::TimeDelta::FromMilliseconds(100), 10.0, 1.0, 5,
+                           1);
 
   // ordinal_offset is invariant to the device scale factor.
   EXPECT_EQ(event_handler.scroll_x_offset(),
@@ -1144,7 +1144,7 @@ TEST_F(DisplayControllerTest, TouchScale) {
   Shell::GetInstance()->RemovePreTargetHandler(&event_handler);
 }
 
-TEST_F(DisplayControllerTest, ConvertHostToRootCoords) {
+TEST_F(WindowTreeHostManagerTest, ConvertHostToRootCoords) {
   if (!SupportsMultipleDisplays())
     return;
 
@@ -1206,7 +1206,7 @@ TEST_F(DisplayControllerTest, ConvertHostToRootCoords) {
 
 // Make sure that the compositor based mirroring can switch
 // from/to dock mode.
-TEST_F(DisplayControllerTest, DockToSingle) {
+TEST_F(WindowTreeHostManagerTest, DockToSingle) {
   if (!SupportsMultipleDisplays())
     return;
 
@@ -1234,21 +1234,25 @@ TEST_F(DisplayControllerTest, DockToSingle) {
   display_info_list.push_back(external_display_info);
   display_manager->OnNativeDisplaysChanged(display_info_list);
   EXPECT_EQ(1U, display_manager->GetNumDisplays());
-  EXPECT_FALSE(Shell::GetPrimaryRootWindow()->GetHost()->
-               GetRootTransform().IsIdentityOrIntegerTranslation());
+  EXPECT_FALSE(Shell::GetPrimaryRootWindow()
+                   ->GetHost()
+                   ->GetRootTransform()
+                   .IsIdentityOrIntegerTranslation());
 
   // Switch to single mode and make sure the transform is the one
   // for the internal display.
   display_info_list.clear();
   display_info_list.push_back(internal_display_info);
   display_manager->OnNativeDisplaysChanged(display_info_list);
-  EXPECT_TRUE(Shell::GetPrimaryRootWindow()->GetHost()->
-              GetRootTransform().IsIdentityOrIntegerTranslation());
+  EXPECT_TRUE(Shell::GetPrimaryRootWindow()
+                  ->GetHost()
+                  ->GetRootTransform()
+                  .IsIdentityOrIntegerTranslation());
 }
 
 // Tests if switching two displays at the same time while the primary display
 // is swapped should not cause a crash. (crbug.com/426292)
-TEST_F(DisplayControllerTest, ReplaceSwappedPrimary) {
+TEST_F(WindowTreeHostManagerTest, ReplaceSwappedPrimary) {
   if (!SupportsMultipleDisplays())
     return;
   DisplayManager* display_manager = Shell::GetInstance()->display_manager();
@@ -1264,7 +1268,7 @@ TEST_F(DisplayControllerTest, ReplaceSwappedPrimary) {
   display_info_list.push_back(second_display_info);
   display_manager->OnNativeDisplaysChanged(display_info_list);
 
-  Shell::GetInstance()->display_controller()->SwapPrimaryDisplay();
+  Shell::GetInstance()->window_tree_host_manager()->SwapPrimaryDisplay();
 
   EXPECT_EQ(11, Shell::GetScreen()->GetPrimaryDisplay().id());
 
@@ -1280,7 +1284,7 @@ TEST_F(DisplayControllerTest, ReplaceSwappedPrimary) {
   EXPECT_EQ(20, Shell::GetScreen()->GetPrimaryDisplay().id());
 }
 
-TEST_F(DisplayControllerTest, UpdateMouseLocationAfterDisplayChange) {
+TEST_F(WindowTreeHostManagerTest, UpdateMouseLocationAfterDisplayChange) {
   if (!SupportsMultipleDisplays())
     return;
 
@@ -1323,7 +1327,8 @@ TEST_F(DisplayControllerTest, UpdateMouseLocationAfterDisplayChange) {
   EXPECT_EQ("450,10", env->last_mouse_location().ToString());
 }
 
-TEST_F(DisplayControllerTest, UpdateMouseLocationAfterDisplayChange_2ndOnLeft) {
+TEST_F(WindowTreeHostManagerTest,
+       UpdateMouseLocationAfterDisplayChange_2ndOnLeft) {
   if (!SupportsMultipleDisplays())
     return;
 
@@ -1363,7 +1368,7 @@ TEST_F(DisplayControllerTest, UpdateMouseLocationAfterDisplayChange_2ndOnLeft) {
 
 // Test that the cursor swaps displays and that its scale factor and rotation
 // are updated when the primary display is swapped.
-TEST_F(DisplayControllerTest,
+TEST_F(WindowTreeHostManagerTest,
        UpdateMouseLocationAfterDisplayChange_SwapPrimary) {
   if (!SupportsMultipleDisplays())
     return;
@@ -1372,16 +1377,18 @@ TEST_F(DisplayControllerTest,
 
   aura::Env* env = aura::Env::GetInstance();
   Shell* shell = Shell::GetInstance();
-  DisplayController* display_controller = shell->display_controller();
+  WindowTreeHostManager* window_tree_host_manager =
+      shell->window_tree_host_manager();
   test::CursorManagerTestApi test_api(shell->cursor_manager());
 
-  display_controller->GetPrimaryRootWindow()->MoveCursorTo(gfx::Point(20, 50));
+  window_tree_host_manager->GetPrimaryRootWindow()->MoveCursorTo(
+      gfx::Point(20, 50));
 
   EXPECT_EQ("20,50", env->last_mouse_location().ToString());
   EXPECT_EQ(1.0f, test_api.GetCurrentCursor().device_scale_factor());
   EXPECT_EQ(gfx::Display::ROTATE_0, test_api.GetCurrentCursorRotation());
 
-  display_controller->SwapPrimaryDisplay();
+  window_tree_host_manager->SwapPrimaryDisplay();
 
   EXPECT_EQ("20,50", env->last_mouse_location().ToString());
   EXPECT_EQ(2.0f, test_api.GetCurrentCursor().device_scale_factor());
@@ -1390,30 +1397,33 @@ TEST_F(DisplayControllerTest,
 
 // Test that the cursor moves to the other display and that its scale factor
 // and rotation are updated when the primary display is disconnected.
-TEST_F(DisplayControllerTest,
+TEST_F(WindowTreeHostManagerTest,
        UpdateMouseLocationAfterDisplayChange_PrimaryDisconnected) {
   if (!SupportsMultipleDisplays())
     return;
 
   aura::Env* env = aura::Env::GetInstance();
   Shell* shell = Shell::GetInstance();
-  DisplayController* display_controller = shell->display_controller();
+  WindowTreeHostManager* window_tree_host_manager =
+      shell->window_tree_host_manager();
   test::CursorManagerTestApi test_api(shell->cursor_manager());
 
   UpdateDisplay("300x300*2/r,200x200");
   // Swap the primary display to make it possible to remove the primary display
   // via UpdateDisplay().
-  display_controller->SwapPrimaryDisplay();
-  int primary_display_id = display_controller->GetPrimaryDisplayId();
+  window_tree_host_manager->SwapPrimaryDisplay();
+  int primary_display_id = window_tree_host_manager->GetPrimaryDisplayId();
 
-  display_controller->GetPrimaryRootWindow()->MoveCursorTo(gfx::Point(20, 50));
+  window_tree_host_manager->GetPrimaryRootWindow()->MoveCursorTo(
+      gfx::Point(20, 50));
 
   EXPECT_EQ("20,50", env->last_mouse_location().ToString());
   EXPECT_EQ(1.0f, test_api.GetCurrentCursor().device_scale_factor());
   EXPECT_EQ(gfx::Display::ROTATE_0, test_api.GetCurrentCursorRotation());
 
   UpdateDisplay("300x300*2/r");
-  ASSERT_NE(primary_display_id, display_controller->GetPrimaryDisplayId());
+  ASSERT_NE(primary_display_id,
+            window_tree_host_manager->GetPrimaryDisplayId());
 
   // Cursor should be centered on the remaining display.
   EXPECT_EQ("75,75", env->last_mouse_location().ToString());
@@ -1423,15 +1433,16 @@ TEST_F(DisplayControllerTest,
 
 // GetRootWindowForDisplayId() for removed gfx::Display during
 // OnDisplayRemoved() should not cause crash. See http://crbug.com/415222
-TEST_F(DisplayControllerTest,
+TEST_F(WindowTreeHostManagerTest,
        GetRootWindowForDisplayIdDuringDisplayDisconnection) {
   if (!SupportsMultipleDisplays())
     return;
 
   UpdateDisplay("300x300,200x200");
   aura::Window* root2 =
-      Shell::GetInstance()->display_controller()->GetRootWindowForDisplayId(
-          ScreenUtil::GetSecondaryDisplay().id());
+      Shell::GetInstance()
+          ->window_tree_host_manager()
+          ->GetRootWindowForDisplayId(ScreenUtil::GetSecondaryDisplay().id());
   views::Widget* widget = views::Widget::CreateWindowWithContextAndBounds(
       nullptr, root2, gfx::Rect(350, 0, 100, 100));
   views::View* view = new views::View();
diff --git a/ash/extended_desktop_unittest.cc b/ash/extended_desktop_unittest.cc
index e27bf8b..64eee29 100644
--- a/ash/extended_desktop_unittest.cc
+++ b/ash/extended_desktop_unittest.cc
@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "ash/display/display_controller.h"
 #include "ash/display/display_manager.h"
 #include "ash/root_window_controller.h"
 #include "ash/screen_util.h"
diff --git a/ash/root_window_controller.h b/ash/root_window_controller.h
index 44d1b40..ffa19e1 100644
--- a/ash/root_window_controller.h
+++ b/ash/root_window_controller.h
@@ -74,7 +74,7 @@ class AshTouchExplorationManager;
 // This class maintains the per root window state for ash. This class
 // owns the root window and other dependent objects that should be
 // deleted upon the deletion of the root window. This object is
-// indirectly owned and deleted by |DisplayController|.
+// indirectly owned and deleted by |WindowTreeHostManager|.
 // The RootWindowController for particular root window is stored in
 // its property (RootWindowSettings) and can be obtained using
 // |GetRootWindowController(aura::WindowEventDispatcher*)| function.
diff --git a/ash/rotator/screen_rotation_animator.cc b/ash/rotator/screen_rotation_animator.cc
index 9b746b6..1df099b 100644
--- a/ash/rotator/screen_rotation_animator.cc
+++ b/ash/rotator/screen_rotation_animator.cc
@@ -8,9 +8,9 @@
 #include <vector>
 
 #include "ash/ash_switches.h"
-#include "ash/display/display_controller.h"
 #include "ash/display/display_info.h"
 #include "ash/display/display_manager.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/rotator/screen_rotation_animation.h"
 #include "ash/shell.h"
 #include "base/command_line.h"
@@ -171,9 +171,9 @@ void RotateScreen(int64 display_id,
                   int rotation_degree_offset,
                   gfx::Tween::Type tween_type,
                   bool should_scale) {
-  aura::Window* root_window =
-      Shell::GetInstance()->display_controller()->GetRootWindowForDisplayId(
-          display_id);
+  aura::Window* root_window = Shell::GetInstance()
+                                  ->window_tree_host_manager()
+                                  ->GetRootWindowForDisplayId(display_id);
 
   const gfx::Display::Rotation initial_orientation =
       GetCurrentRotation(display_id);
diff --git a/ash/screen_util.cc b/ash/screen_util.cc
index bd4f22d..d0e4121 100644
--- a/ash/screen_util.cc
+++ b/ash/screen_util.cc
@@ -4,7 +4,6 @@
 
 #include "ash/screen_util.h"
 
-#include "ash/display/display_controller.h"
 #include "ash/display/display_manager.h"
 #include "ash/root_window_controller.h"
 #include "ash/shelf/shelf_layout_manager.h"
diff --git a/ash/shelf/shelf_layout_manager_unittest.cc b/ash/shelf/shelf_layout_manager_unittest.cc
index b737e80..d447b06 100644
--- a/ash/shelf/shelf_layout_manager_unittest.cc
+++ b/ash/shelf/shelf_layout_manager_unittest.cc
@@ -7,8 +7,8 @@
 #include "ash/accelerators/accelerator_controller.h"
 #include "ash/accelerators/accelerator_table.h"
 #include "ash/ash_switches.h"
-#include "ash/display/display_controller.h"
 #include "ash/display/display_manager.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/focus_cycler.h"
 #include "ash/root_window_controller.h"
 #include "ash/session/session_state_delegate.h"
@@ -1221,8 +1221,10 @@ TEST_F(ShelfLayoutManagerTest, DimmingBehaviorDualDisplay) {
   UpdateDisplay("0+0-200x200,+200+0-100x100");
   EXPECT_EQ(2U, shell->display_manager()->GetNumDisplays());
 
-  DisplayController* display_controller = shell->display_controller();
-  aura::Window::Windows root_windows = display_controller->GetAllRootWindows();
+  WindowTreeHostManager* window_tree_host_manager =
+      shell->window_tree_host_manager();
+  aura::Window::Windows root_windows =
+      window_tree_host_manager->GetAllRootWindows();
   EXPECT_EQ(root_windows.size(), 2U);
 
   std::vector<ShelfWidget*> shelf_widgets;
@@ -1449,8 +1451,10 @@ TEST_F(ShelfLayoutManagerTest, DualDisplayOpenAppListWithShelfAutoHideState) {
   UpdateDisplay("0+0-200x200,+200+0-100x100");
   EXPECT_EQ(2U, display_manager->GetNumDisplays());
 
-  DisplayController* display_controller = shell->display_controller();
-  aura::Window::Windows root_windows = display_controller->GetAllRootWindows();
+  WindowTreeHostManager* window_tree_host_manager =
+      shell->window_tree_host_manager();
+  aura::Window::Windows root_windows =
+      window_tree_host_manager->GetAllRootWindows();
   EXPECT_EQ(root_windows.size(), 2U);
 
   // Get the shelves in both displays and set them to be 'AutoHide'.
@@ -1582,8 +1586,10 @@ TEST_F(ShelfLayoutManagerTest, ShelfWithSystemModalWindowDualDisplay) {
   UpdateDisplay("200x200,100x100");
   EXPECT_EQ(2U, display_manager->GetNumDisplays());
 
-  DisplayController* display_controller = shell->display_controller();
-  aura::Window::Windows root_windows = display_controller->GetAllRootWindows();
+  WindowTreeHostManager* window_tree_host_manager =
+      shell->window_tree_host_manager();
+  aura::Window::Windows root_windows =
+      window_tree_host_manager->GetAllRootWindows();
   EXPECT_EQ(2U, root_windows.size());
 
   // Get the shelves in both displays and set them to be 'AutoHide'.
diff --git a/ash/shelf/shelf_window_watcher.cc b/ash/shelf/shelf_window_watcher.cc
index 546d212..4bdb024 100644
--- a/ash/shelf/shelf_window_watcher.cc
+++ b/ash/shelf/shelf_window_watcher.cc
@@ -4,7 +4,7 @@
 
 #include "ash/shelf/shelf_window_watcher.h"
 
-#include "ash/display/display_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/shelf/shelf_constants.h"
 #include "ash/shelf/shelf_item_delegate_manager.h"
 #include "ash/shelf/shelf_model.h"
@@ -268,8 +268,9 @@ void ShelfWindowWatcher::OnWindowPropertyChanged(aura::Window* window,
 
 void ShelfWindowWatcher::OnDisplayAdded(const gfx::Display& new_display) {
   // Add a new RootWindow and its ActivationClient to observed list.
-  aura::Window* root_window = Shell::GetInstance()->display_controller()->
-      GetRootWindowForDisplayId(new_display.id());
+  aura::Window* root_window = Shell::GetInstance()
+                                  ->window_tree_host_manager()
+                                  ->GetRootWindowForDisplayId(new_display.id());
 
   // When the primary root window's display get removed, the existing root
   // window is taken over by the new display and the observer is already set.
diff --git a/ash/shell.cc b/ash/shell.cc
index c67beb3..4cbc6d4 100644
--- a/ash/shell.cc
+++ b/ash/shell.cc
@@ -17,11 +17,11 @@
 #include "ash/desktop_background/desktop_background_view.h"
 #include "ash/desktop_background/user_wallpaper_delegate.h"
 #include "ash/display/cursor_window_controller.h"
-#include "ash/display/display_controller.h"
 #include "ash/display/display_manager.h"
 #include "ash/display/event_transformation_handler.h"
 #include "ash/display/mouse_cursor_event_filter.h"
 #include "ash/display/screen_position_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/drag_drop/drag_drop_controller.h"
 #include "ash/first_run/first_run_helper_impl.h"
 #include "ash/focus_cycler.h"
@@ -222,14 +222,15 @@ RootWindowController* Shell::GetPrimaryRootWindowController() {
 // static
 Shell::RootWindowControllerList Shell::GetAllRootWindowControllers() {
   CHECK(HasInstance());
-  return Shell::GetInstance()->display_controller()->
-      GetAllRootWindowControllers();
+  return Shell::GetInstance()
+      ->window_tree_host_manager()
+      ->GetAllRootWindowControllers();
 }
 
 // static
 aura::Window* Shell::GetPrimaryRootWindow() {
   CHECK(HasInstance());
-  return GetInstance()->display_controller()->GetPrimaryRootWindow();
+  return GetInstance()->window_tree_host_manager()->GetPrimaryRootWindow();
 }
 
 // static
@@ -249,8 +250,7 @@ gfx::Screen* Shell::GetScreen() {
 // static
 aura::Window::Windows Shell::GetAllRootWindows() {
   CHECK(HasInstance());
-  return Shell::GetInstance()->display_controller()->
-      GetAllRootWindows();
+  return Shell::GetInstance()->window_tree_host_manager()->GetAllRootWindows();
 }
 
 // static
@@ -367,7 +367,7 @@ void Shell::RotateFocus(Direction direction) {
 
 void Shell::SetDisplayWorkAreaInsets(Window* contains,
                                      const gfx::Insets& insets) {
-  if (!display_controller_->UpdateWorkAreaOfDisplayNearestWindow(
+  if (!window_tree_host_manager_->UpdateWorkAreaOfDisplayNearestWindow(
           contains, insets)) {
     return;
   }
@@ -618,8 +618,8 @@ ash::FirstRunHelper* Shell::CreateFirstRunHelper() {
 }
 
 void Shell::SetCursorCompositingEnabled(bool enabled) {
-  display_controller_->cursor_window_controller()->SetCursorCompositingEnabled(
-      enabled);
+  window_tree_host_manager_->cursor_window_controller()
+      ->SetCursorCompositingEnabled(enabled);
   native_cursor_manager_->SetNativeCursorEnabled(!enabled);
 }
 #endif  // defined(OS_CHROMEOS)
@@ -649,7 +649,7 @@ Shell::Shell(ShellDelegate* delegate)
   DCHECK(delegate_.get());
   gpu_support_.reset(delegate_->CreateGPUSupport());
   display_manager_.reset(new DisplayManager);
-  display_controller_.reset(new DisplayController);
+  window_tree_host_manager_.reset(new WindowTreeHostManager);
   user_metrics_recorder_.reset(new UserMetricsRecorder);
 
 #if defined(OS_CHROMEOS)
@@ -674,7 +674,8 @@ Shell::~Shell() {
   // Please keep in same order as in Init() because it's easy to miss one.
   if (window_modality_controller_)
     window_modality_controller_.reset();
-  RemovePreTargetHandler(display_controller_->input_method_event_handler());
+  RemovePreTargetHandler(
+      window_tree_host_manager_->input_method_event_handler());
 #if defined(OS_CHROMEOS)
   RemovePreTargetHandler(magnifier_key_scroll_handler_.get());
   magnifier_key_scroll_handler_.reset();
@@ -734,7 +735,7 @@ Shell::~Shell() {
   drag_drop_controller_.reset();
 
   // Controllers who have WindowObserver added must be deleted
-  // before |display_controller_| is deleted.
+  // before |window_tree_host_manager_| is deleted.
 
 #if defined(OS_CHROMEOS)
   // VideoActivityNotifier must be deleted before |video_detector_| is
@@ -756,7 +757,7 @@ Shell::~Shell() {
   shelf_window_watcher_.reset();
 
   // Destroy all child windows including widgets.
-  display_controller_->CloseChildWindows();
+  window_tree_host_manager_->CloseChildWindows();
   // MruWindowTracker must be destroyed after all windows have been deleted to
   // avoid a possible crash when Shell is destroyed from a non-normal shutdown
   // path. (crbug.com/485438).
@@ -801,11 +802,12 @@ Shell::~Shell() {
 #endif  // defined(OS_CHROMEOS)
 
   // This also deletes all RootWindows. Note that we invoke Shutdown() on
-  // DisplayController before resetting |display_controller_|, since destruction
+  // WindowTreeHostManager before resetting |window_tree_host_manager_|, since
+  // destruction
   // of its owned RootWindowControllers relies on the value.
   display_manager_->CreateScreenForShutdown();
-  display_controller_->Shutdown();
-  display_controller_.reset();
+  window_tree_host_manager_->Shutdown();
+  window_tree_host_manager_.reset();
   screen_position_controller_.reset();
   accessibility_delegate_.reset();
   new_window_delegate_.reset();
@@ -902,10 +904,10 @@ void Shell::Init(const ShellInitParams& init_params) {
 
   screen_position_controller_.reset(new ScreenPositionController);
 
-  display_controller_->Start();
-  display_controller_->CreatePrimaryHost(
+  window_tree_host_manager_->Start();
+  window_tree_host_manager_->CreatePrimaryHost(
       ShellInitParamsToAshWindowTreeHostInitParams(init_params));
-  aura::Window* root_window = display_controller_->GetPrimaryRootWindow();
+  aura::Window* root_window = window_tree_host_manager_->GetPrimaryRootWindow();
   target_root_window_ = root_window;
 
 #if defined(OS_CHROMEOS)
@@ -920,7 +922,7 @@ void Shell::Init(const ShellInitParams& init_params) {
   accelerator_controller_.reset(new AcceleratorController);
   maximize_mode_controller_.reset(new MaximizeModeController());
 
-  AddPreTargetHandler(display_controller_->input_method_event_handler());
+  AddPreTargetHandler(window_tree_host_manager_->input_method_event_handler());
 
 #if defined(OS_CHROMEOS)
   magnifier_key_scroll_handler_ = MagnifierKeyScroller::CreateHandler();
@@ -1041,13 +1043,14 @@ void Shell::Init(const ShellInitParams& init_params) {
       base::Bind(&SystemTrayDelegate::SignOut,
                  base::Unretained(system_tray_delegate_.get()))));
 
-  // Create TouchTransformerController before DisplayController::InitDisplays()
+  // Create TouchTransformerController before
+  // WindowTreeHostManager::InitDisplays()
   // since TouchTransformerController listens on
-  // DisplayController::Observer::OnDisplaysInitialized().
+  // WindowTreeHostManager::Observer::OnDisplaysInitialized().
   touch_transformer_controller_.reset(new TouchTransformerController());
 #endif  // defined(OS_CHROMEOS)
 
-  display_controller_->InitDisplays();
+  window_tree_host_manager_->InitHosts();
 
 #if defined(OS_CHROMEOS)
   // Needs to be created after InitDisplays() since it may cause the virtual
diff --git a/ash/shell.h b/ash/shell.h
index db196e6..d2480a8 100644
--- a/ash/shell.h
+++ b/ash/shell.h
@@ -84,7 +84,7 @@ class DesktopBackgroundController;
 class DisplayChangeObserver;
 class DisplayColorManager;
 class DisplayConfiguratorAnimation;
-class DisplayController;
+class WindowTreeHostManager;
 class DisplayErrorObserver;
 class DisplayManager;
 class DragDropController;
@@ -374,8 +374,8 @@ class ASH_EXPORT Shell : public SystemModalContainerEventFilterDelegate,
     return window_selector_controller_.get();
   }
   FocusCycler* focus_cycler() { return focus_cycler_.get(); }
-  DisplayController* display_controller() {
-    return display_controller_.get();
+  WindowTreeHostManager* window_tree_host_manager() {
+    return window_tree_host_manager_.get();
   }
 #if defined(OS_CHROMEOS)
   PowerEventObserver* power_event_observer() {
@@ -514,7 +514,7 @@ class ASH_EXPORT Shell : public SystemModalContainerEventFilterDelegate,
   }
 
 #if defined(OS_CHROMEOS)
-  // TODO(oshima): Move these objects to DisplayController.
+  // TODO(oshima): Move these objects to WindowTreeHostManager.
   ui::DisplayConfigurator* display_configurator() {
     return display_configurator_.get();
   }
@@ -671,7 +671,7 @@ class ASH_EXPORT Shell : public SystemModalContainerEventFilterDelegate,
   scoped_ptr<WindowCycleController> window_cycle_controller_;
   scoped_ptr<WindowSelectorController> window_selector_controller_;
   scoped_ptr<FocusCycler> focus_cycler_;
-  scoped_ptr<DisplayController> display_controller_;
+  scoped_ptr<WindowTreeHostManager> window_tree_host_manager_;
   scoped_ptr<HighContrastController> high_contrast_controller_;
   scoped_ptr<MagnificationController> magnification_controller_;
   scoped_ptr<PartialMagnificationController> partial_magnification_controller_;
diff --git a/ash/shell/toplevel_window.cc b/ash/shell/toplevel_window.cc
index 27c96d6..ab9cdc4 100644
--- a/ash/shell/toplevel_window.cc
+++ b/ash/shell/toplevel_window.cc
@@ -4,7 +4,6 @@
 
 #include "ash/shell/toplevel_window.h"
 
-#include "ash/display/display_controller.h"
 #include "ash/shell.h"
 #include "ash/wm/window_positioner.h"
 #include "ash/wm/window_state.h"
diff --git a/ash/shell/window_watcher.cc b/ash/shell/window_watcher.cc
index f5b194c..bd5d148 100644
--- a/ash/shell/window_watcher.cc
+++ b/ash/shell/window_watcher.cc
@@ -4,7 +4,7 @@
 
 #include "ash/shell/window_watcher.h"
 
-#include "ash/display/display_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/shelf/shelf.h"
 #include "ash/shelf/shelf_item_delegate_manager.h"
 #include "ash/shelf/shelf_model.h"
@@ -137,8 +137,9 @@ void WindowWatcher::OnWillRemoveWindow(aura::Window* window) {
 }
 
 void WindowWatcher::OnDisplayAdded(const gfx::Display& new_display) {
-  aura::Window* root = Shell::GetInstance()->display_controller()->
-      GetRootWindowForDisplayId(new_display.id());
+  aura::Window* root = Shell::GetInstance()
+                           ->window_tree_host_manager()
+                           ->GetRootWindowForDisplayId(new_display.id());
   workspace_window_watcher_->RootWindowAdded(root);
 }
 
diff --git a/ash/sticky_keys/sticky_keys_overlay_unittest.cc b/ash/sticky_keys/sticky_keys_overlay_unittest.cc
index 2566a8b..d28c536 100644
--- a/ash/sticky_keys/sticky_keys_overlay_unittest.cc
+++ b/ash/sticky_keys/sticky_keys_overlay_unittest.cc
@@ -4,8 +4,8 @@
 
 #include "ash/sticky_keys/sticky_keys_overlay.h"
 
-#include "ash/display/display_controller.h"
 #include "ash/display/display_manager.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/shell.h"
 #include "ash/sticky_keys/sticky_keys_controller.h"
 #include "ash/test/ash_test_base.h"
@@ -55,16 +55,18 @@ TEST_F(StickyKeysOverlayTest, OverlayNotDestroyedAfterDisplayRemoved) {
   // The overlay should belong to the secondary root window.
   StickyKeysOverlay overlay;
   views::Widget* overlay_widget = overlay.GetWidgetForTesting();
-  DisplayController* display_controller =
-      Shell::GetInstance()->display_controller();
-  EXPECT_EQ(display_controller->GetRootWindowForDisplayId(secondary_display_id),
-            overlay_widget->GetNativeWindow()->GetRootWindow());
+  WindowTreeHostManager* window_tree_host_manager =
+      Shell::GetInstance()->window_tree_host_manager();
+  EXPECT_EQ(
+      window_tree_host_manager->GetRootWindowForDisplayId(secondary_display_id),
+      overlay_widget->GetNativeWindow()->GetRootWindow());
 
   // Removing the second display should move the overlay to the primary root
   // window.
   UpdateDisplay("1280x1024");
-  EXPECT_EQ(display_controller->GetRootWindowForDisplayId(primary_display_id),
-            overlay_widget->GetNativeWindow()->GetRootWindow());
+  EXPECT_EQ(
+      window_tree_host_manager->GetRootWindowForDisplayId(primary_display_id),
+      overlay_widget->GetNativeWindow()->GetRootWindow());
 
   overlay.SetModifierKeyState(ui::EF_SHIFT_DOWN, STICKY_KEY_STATE_ENABLED);
   EXPECT_EQ(STICKY_KEY_STATE_ENABLED,
diff --git a/ash/system/chromeos/tray_display.cc b/ash/system/chromeos/tray_display.cc
index be9adec..6f4142b 100644
--- a/ash/system/chromeos/tray_display.cc
+++ b/ash/system/chromeos/tray_display.cc
@@ -7,8 +7,8 @@
 #include <vector>
 
 #include "ash/content/display/screen_orientation_controller_chromeos.h"
-#include "ash/display/display_controller.h"
 #include "ash/display/display_manager.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/shell.h"
 #include "ash/system/chromeos/devicetype_utils.h"
 #include "ash/system/system_notifier.h"
@@ -293,12 +293,12 @@ class DisplayView : public ActionableView {
 TrayDisplay::TrayDisplay(SystemTray* system_tray)
     : SystemTrayItem(system_tray),
       default_(NULL) {
-  Shell::GetInstance()->display_controller()->AddObserver(this);
+  Shell::GetInstance()->window_tree_host_manager()->AddObserver(this);
   UpdateDisplayInfo(NULL);
 }
 
 TrayDisplay::~TrayDisplay() {
-  Shell::GetInstance()->display_controller()->RemoveObserver(this);
+  Shell::GetInstance()->window_tree_host_manager()->RemoveObserver(this);
 }
 
 void TrayDisplay::UpdateDisplayInfo(TrayDisplay::DisplayInfoMap* old_info) {
diff --git a/ash/system/chromeos/tray_display.h b/ash/system/chromeos/tray_display.h
index 72b0980..08309ce 100644
--- a/ash/system/chromeos/tray_display.h
+++ b/ash/system/chromeos/tray_display.h
@@ -8,8 +8,8 @@
 #include <map>
 
 #include "ash/ash_export.h"
-#include "ash/display/display_controller.h"
 #include "ash/display/display_info.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/system/tray/system_tray_item.h"
 #include "base/strings/string16.h"
 #include "ui/views/view.h"
@@ -22,12 +22,12 @@ class AshTestBase;
 }
 
 class ASH_EXPORT TrayDisplay : public SystemTrayItem,
-                               public DisplayController::Observer {
+                               public WindowTreeHostManager::Observer {
  public:
   explicit TrayDisplay(SystemTray* system_tray);
   ~TrayDisplay() override;
 
-  // Overridden from DisplayControllerObserver:
+  // Overridden from WindowTreeHostManagerObserver:
   void OnDisplayConfigurationChanged() override;
 
  private:
diff --git a/ash/system/web_notification/ash_popup_alignment_delegate.cc b/ash/system/web_notification/ash_popup_alignment_delegate.cc
index 0c77877..a452f18 100644
--- a/ash/system/web_notification/ash_popup_alignment_delegate.cc
+++ b/ash/system/web_notification/ash_popup_alignment_delegate.cc
@@ -4,7 +4,7 @@
 
 #include "ash/system/web_notification/ash_popup_alignment_delegate.h"
 
-#include "ash/display/display_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/screen_util.h"
 #include "ash/shelf/shelf_constants.h"
 #include "ash/shelf/shelf_layout_manager.h"
@@ -49,7 +49,7 @@ void AshPopupAlignmentDelegate::StartObserving(gfx::Screen* screen,
   screen_ = screen;
   work_area_ = display.work_area();
   root_window_ = ash::Shell::GetInstance()
-                     ->display_controller()
+                     ->window_tree_host_manager()
                      ->GetRootWindowForDisplayId(display.id());
   UpdateShelf();
   screen->AddObserver(this);
diff --git a/ash/test/ash_test_base.cc b/ash/test/ash_test_base.cc
index f483044..dc0e36e 100644
--- a/ash/test/ash_test_base.cc
+++ b/ash/test/ash_test_base.cc
@@ -8,7 +8,7 @@
 #include <vector>
 
 #include "ash/ash_switches.h"
-#include "ash/display/display_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/ime/input_method_event_handler.h"
 #include "ash/shell.h"
 #include "ash/shell/toplevel_window.h"
@@ -68,8 +68,10 @@ class AshEventGeneratorDelegate
       const gfx::Point& point_in_screen) const override {
     gfx::Screen* screen = Shell::GetScreen();
     gfx::Display display = screen->GetDisplayNearestPoint(point_in_screen);
-    return Shell::GetInstance()->display_controller()->
-        GetRootWindowForDisplayId(display.id())->GetHost();
+    return Shell::GetInstance()
+        ->window_tree_host_manager()
+        ->GetRootWindowForDisplayId(display.id())
+        ->GetHost();
   }
 
   aura::client::ScreenPositionClient* GetScreenPositionClient(
@@ -271,8 +273,9 @@ aura::Window* AshTestBase::CreateTestWindowInShellWithDelegateAndType(
   } else {
     gfx::Display display =
         Shell::GetScreen()->GetDisplayMatching(bounds);
-    aura::Window* root = ash::Shell::GetInstance()->display_controller()->
-        GetRootWindowForDisplayId(display.id());
+    aura::Window* root = ash::Shell::GetInstance()
+                             ->window_tree_host_manager()
+                             ->GetRootWindowForDisplayId(display.id());
     gfx::Point origin = bounds.origin();
     ::wm::ConvertPointFromScreen(root, &origin);
     window->SetBounds(gfx::Rect(origin, bounds.size()));
@@ -361,7 +364,9 @@ void AshTestBase::UnblockUserSession() {
 
 void AshTestBase::DisableIME() {
   Shell::GetInstance()->RemovePreTargetHandler(
-      Shell::GetInstance()->display_controller()->input_method_event_handler());
+      Shell::GetInstance()
+          ->window_tree_host_manager()
+          ->input_method_event_handler());
 }
 
 }  // namespace test
diff --git a/ash/test/mirror_window_test_api.cc b/ash/test/mirror_window_test_api.cc
index a66417a..5f687f8 100644
--- a/ash/test/mirror_window_test_api.cc
+++ b/ash/test/mirror_window_test_api.cc
@@ -5,9 +5,9 @@
 #include "ash/test/mirror_window_test_api.h"
 
 #include "ash/display/cursor_window_controller.h"
-#include "ash/display/display_controller.h"
 #include "ash/display/mirror_window_controller.h"
 #include "ash/display/root_window_transformers.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/host/root_window_transformer.h"
 #include "ash/shell.h"
 #include "ui/gfx/geometry/point.h"
@@ -17,20 +17,24 @@ namespace test {
 
 const aura::WindowTreeHost* MirrorWindowTestApi::GetHost() const {
   aura::Window* window = Shell::GetInstance()
-                             ->display_controller()
+                             ->window_tree_host_manager()
                              ->mirror_window_controller()
                              ->GetWindow();
   return window ? window->GetHost() : NULL;
 }
 
 int MirrorWindowTestApi::GetCurrentCursorType() const {
-  return Shell::GetInstance()->display_controller()->
-      cursor_window_controller()->cursor_type_;
+  return Shell::GetInstance()
+      ->window_tree_host_manager()
+      ->cursor_window_controller()
+      ->cursor_type_;
 }
 
 const gfx::Point& MirrorWindowTestApi::GetCursorHotPoint() const {
-  return Shell::GetInstance()->display_controller()->
-      cursor_window_controller()->hot_point_;
+  return Shell::GetInstance()
+      ->window_tree_host_manager()
+      ->cursor_window_controller()
+      ->hot_point_;
 }
 
 gfx::Point MirrorWindowTestApi::GetCursorHotPointLocationInRootWindow() const {
@@ -39,8 +43,10 @@ gfx::Point MirrorWindowTestApi::GetCursorHotPointLocationInRootWindow() const {
 }
 
 const aura::Window* MirrorWindowTestApi::GetCursorWindow() const {
-  return Shell::GetInstance()->display_controller()->
-      cursor_window_controller()->cursor_window_.get();
+  return Shell::GetInstance()
+      ->window_tree_host_manager()
+      ->cursor_window_controller()
+      ->cursor_window_.get();
 }
 
 gfx::Point MirrorWindowTestApi::GetCursorLocation() const {
diff --git a/ash/touch/touch_observer_hud.cc b/ash/touch/touch_observer_hud.cc
index 02f85ad..1ace7fd 100644
--- a/ash/touch/touch_observer_hud.cc
+++ b/ash/touch/touch_observer_hud.cc
@@ -51,12 +51,12 @@ TouchObserverHUD::TouchObserverHUD(aura::Window* initial_root)
   Shell::GetInstance()->display_configurator()->AddObserver(this);
 #endif  // defined(OS_CHROMEOS)
 
-  Shell::GetInstance()->display_controller()->AddObserver(this);
+  Shell::GetInstance()->window_tree_host_manager()->AddObserver(this);
   root_window_->AddPreTargetHandler(this);
 }
 
 TouchObserverHUD::~TouchObserverHUD() {
-  Shell::GetInstance()->display_controller()->RemoveObserver(this);
+  Shell::GetInstance()->window_tree_host_manager()->RemoveObserver(this);
 
 #if defined(OS_CHROMEOS)
   Shell::GetInstance()->display_configurator()->RemoveObserver(this);
@@ -136,8 +136,9 @@ void TouchObserverHUD::OnDisplayConfigurationChanged() {
   if (root_window_)
     return;
 
-  root_window_ = Shell::GetInstance()->display_controller()->
-      GetRootWindowForDisplayId(display_id_);
+  root_window_ = Shell::GetInstance()
+                     ->window_tree_host_manager()
+                     ->GetRootWindowForDisplayId(display_id_);
 
   views::Widget::ReparentNativeView(
       widget_->GetNativeView(),
diff --git a/ash/touch/touch_observer_hud.h b/ash/touch/touch_observer_hud.h
index e678372..1a558ee 100644
--- a/ash/touch/touch_observer_hud.h
+++ b/ash/touch/touch_observer_hud.h
@@ -6,7 +6,7 @@
 #define ASH_TOUCH_TOUCH_OBSERVER_HUD_H_
 
 #include "ash/ash_export.h"
-#include "ash/display/display_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ui/events/event_handler.h"
 #include "ui/gfx/display_observer.h"
 #include "ui/views/widget/widget_observer.h"
@@ -29,7 +29,7 @@ class ASH_EXPORT TouchObserverHUD : public ui::EventHandler,
 #if defined(OS_CHROMEOS)
                                     public ui::DisplayConfigurator::Observer,
 #endif  // defined(OS_CHROMEOS)
-                                    public DisplayController::Observer {
+                                    public WindowTreeHostManager::Observer {
  public:
   // Called to clear touch points and traces from the screen. Default
   // implementation does nothing. Sub-classes should implement appropriately.
@@ -70,7 +70,7 @@ class ASH_EXPORT TouchObserverHUD : public ui::EventHandler,
       const ui::DisplayConfigurator::DisplayStateList& outputs) override;
 #endif  // defined(OS_CHROMEOS)
 
-  // Overriden form DisplayController::Observer.
+  // Overriden form WindowTreeHostManager::Observer.
   void OnDisplaysInitialized() override;
   void OnDisplayConfigurationChanging() override;
   void OnDisplayConfigurationChanged() override;
diff --git a/ash/touch/touch_observer_hud_unittest.cc b/ash/touch/touch_observer_hud_unittest.cc
index 7a3cf22..f7293a5 100644
--- a/ash/touch/touch_observer_hud_unittest.cc
+++ b/ash/touch/touch_observer_hud_unittest.cc
@@ -68,13 +68,13 @@ class TouchHudTestBase : public test::AshTestBase {
   void SetInternalAsPrimary() {
     const gfx::Display& internal_display =
         GetDisplayManager()->GetDisplayForId(internal_display_id_);
-    GetDisplayController()->SetPrimaryDisplay(internal_display);
+    GetWindowTreeHostManager()->SetPrimaryDisplay(internal_display);
   }
 
   void SetExternalAsPrimary() {
     const gfx::Display& external_display =
         GetDisplayManager()->GetDisplayForId(external_display_id_);
-    GetDisplayController()->SetPrimaryDisplay(external_display);
+    GetWindowTreeHostManager()->SetPrimaryDisplay(external_display);
   }
 
   void MirrorDisplays() {
@@ -131,8 +131,8 @@ class TouchHudTestBase : public test::AshTestBase {
     return Shell::GetInstance()->display_manager();
   }
 
-  DisplayController* GetDisplayController() {
-    return Shell::GetInstance()->display_controller();
+  WindowTreeHostManager* GetWindowTreeHostManager() {
+    return Shell::GetInstance()->window_tree_host_manager();
   }
 
   const gfx::Display& GetInternalDisplay() {
@@ -144,23 +144,23 @@ class TouchHudTestBase : public test::AshTestBase {
   }
 
   aura::Window* GetInternalRootWindow() {
-    return GetDisplayController()->GetRootWindowForDisplayId(
+    return GetWindowTreeHostManager()->GetRootWindowForDisplayId(
         internal_display_id_);
   }
 
   aura::Window* GetExternalRootWindow() {
-    return GetDisplayController()->GetRootWindowForDisplayId(
+    return GetWindowTreeHostManager()->GetRootWindowForDisplayId(
         external_display_id_);
   }
 
   aura::Window* GetPrimaryRootWindow() {
     const gfx::Display& display = GetPrimaryDisplay();
-    return GetDisplayController()->GetRootWindowForDisplayId(display.id());
+    return GetWindowTreeHostManager()->GetRootWindowForDisplayId(display.id());
   }
 
   aura::Window* GetSecondaryRootWindow() {
     const gfx::Display& display = GetSecondaryDisplay();
-    return GetDisplayController()->GetRootWindowForDisplayId(display.id());
+    return GetWindowTreeHostManager()->GetRootWindowForDisplayId(display.id());
   }
 
   RootWindowController* GetInternalRootController() {
diff --git a/ash/touch/touch_transformer_controller.cc b/ash/touch/touch_transformer_controller.cc
index bc4cd64..a419b67 100644
--- a/ash/touch/touch_transformer_controller.cc
+++ b/ash/touch/touch_transformer_controller.cc
@@ -4,8 +4,8 @@
 
 #include "ash/touch/touch_transformer_controller.h"
 
-#include "ash/display/display_controller.h"
 #include "ash/display/display_manager.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/host/ash_window_tree_host.h"
 #include "ash/root_window_controller.h"
 #include "ash/shell.h"
@@ -117,11 +117,11 @@ gfx::Transform TouchTransformerController::GetTouchTransform(
 }
 
 TouchTransformerController::TouchTransformerController() {
-  Shell::GetInstance()->display_controller()->AddObserver(this);
+  Shell::GetInstance()->window_tree_host_manager()->AddObserver(this);
 }
 
 TouchTransformerController::~TouchTransformerController() {
-  Shell::GetInstance()->display_controller()->RemoveObserver(this);
+  Shell::GetInstance()->window_tree_host_manager()->RemoveObserver(this);
 }
 
 void TouchTransformerController::UpdateTouchRadius(
@@ -162,8 +162,8 @@ void TouchTransformerController::UpdateTouchTransformer() const {
   int64 single_display_id = gfx::Display::kInvalidDisplayID;
   DisplayInfo single_display;
 
-  DisplayController* display_controller =
-      Shell::GetInstance()->display_controller();
+  WindowTreeHostManager* window_tree_host_manager =
+      Shell::GetInstance()->window_tree_host_manager();
   DisplayManager* display_manager = GetDisplayManager();
   if (display_manager->num_connected_displays() == 0) {
     return;
@@ -189,7 +189,8 @@ void TouchTransformerController::UpdateTouchTransformer() const {
       Shell::GetInstance()->display_configurator()->framebuffer_size();
 
   if (display_manager->IsInMirrorMode()) {
-    int64_t primary_display_id = display_controller->GetPrimaryDisplayId();
+    int64_t primary_display_id =
+        window_tree_host_manager->GetPrimaryDisplayId();
     if (GetDisplayManager()->SoftwareMirroringEnabled()) {
       // In extended but software mirroring mode, there is a WindowTreeHost for
       // each display, but all touches are forwarded to the primary root
diff --git a/ash/touch/touch_transformer_controller.h b/ash/touch/touch_transformer_controller.h
index bf06f8c..2464b72 100644
--- a/ash/touch/touch_transformer_controller.h
+++ b/ash/touch/touch_transformer_controller.h
@@ -6,7 +6,7 @@
 #define ASH_TOUCH_TOUCH_TRANSFORMER_CONTROLLER_H_
 
 #include "ash/ash_export.h"
-#include "ash/display/display_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ui/gfx/transform.h"
 
 namespace ui {
@@ -18,7 +18,7 @@ namespace ash {
 // TouchTransformerController listens to display configuration change
 // and updates the touch transformation for touch displays.
 class ASH_EXPORT TouchTransformerController
-    : public DisplayController::Observer {
+    : public WindowTreeHostManager::Observer {
  public:
   TouchTransformerController();
   ~TouchTransformerController() override;
@@ -27,7 +27,7 @@ class ASH_EXPORT TouchTransformerController
   // TouchTransformer into device manager.
   void UpdateTouchTransformer() const;
 
-  // DisplayController::Observer:
+  // WindowTreeHostManager::Observer:
   void OnDisplaysInitialized() override;
   void OnDisplayConfigurationChanged() override;
 
diff --git a/ash/utility/partial_screenshot_controller_unittest.cc b/ash/utility/partial_screenshot_controller_unittest.cc
index 423eaf9..71d6619 100644
--- a/ash/utility/partial_screenshot_controller_unittest.cc
+++ b/ash/utility/partial_screenshot_controller_unittest.cc
@@ -5,8 +5,8 @@
 #include "ash/utility/partial_screenshot_controller.h"
 
 #include "ash/display/cursor_window_controller.h"
-#include "ash/display/display_controller.h"
 #include "ash/display/mouse_cursor_event_filter.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/screenshot_delegate.h"
 #include "ash/shell.h"
 #include "ash/test/ash_test_base.h"
@@ -195,7 +195,7 @@ TEST_F(PartialScreenshotControllerTest, VisibilityTest) {
 TEST_F(PartialScreenshotControllerTest, LargeCursor) {
   Shell::GetInstance()->cursor_manager()->SetCursorSet(ui::CURSOR_SET_LARGE);
   Shell::GetInstance()
-      ->display_controller()
+      ->window_tree_host_manager()
       ->cursor_window_controller()
       ->SetCursorCompositingEnabled(true);
 
diff --git a/ash/wm/ash_native_cursor_manager.cc b/ash/wm/ash_native_cursor_manager.cc
index 7f48cad..ef1576b 100644
--- a/ash/wm/ash_native_cursor_manager.cc
+++ b/ash/wm/ash_native_cursor_manager.cc
@@ -5,7 +5,7 @@
 #include "ash/wm/ash_native_cursor_manager.h"
 
 #include "ash/display/cursor_window_controller.h"
-#include "ash/display/display_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/shell.h"
 #include "base/logging.h"
 #include "ui/aura/env.h"
@@ -25,8 +25,10 @@ void SetCursorOnAllRootWindows(gfx::NativeCursor cursor) {
        iter != root_windows.end(); ++iter)
     (*iter)->GetHost()->SetCursor(cursor);
 #if defined(OS_CHROMEOS)
-  Shell::GetInstance()->display_controller()->
-      cursor_window_controller()->SetCursor(cursor);
+  Shell::GetInstance()
+      ->window_tree_host_manager()
+      ->cursor_window_controller()
+      ->SetCursor(cursor);
 #endif
 }
 
@@ -37,8 +39,10 @@ void NotifyCursorVisibilityChange(bool visible) {
        iter != root_windows.end(); ++iter)
     (*iter)->GetHost()->OnCursorVisibilityChanged(visible);
 #if defined(OS_CHROMEOS)
-  Shell::GetInstance()->display_controller()->cursor_window_controller()->
-      SetVisibility(visible);
+  Shell::GetInstance()
+      ->window_tree_host_manager()
+      ->cursor_window_controller()
+      ->SetVisibility(visible);
 #endif
 }
 
@@ -89,8 +93,10 @@ void AshNativeCursorManager::SetDisplay(
   if (image_cursors_->SetDisplay(display, cursor_scale))
     SetCursor(delegate->GetCursor(), delegate);
 #if defined(OS_CHROMEOS)
-  Shell::GetInstance()->display_controller()->cursor_window_controller()->
-      SetDisplay(display);
+  Shell::GetInstance()
+      ->window_tree_host_manager()
+      ->cursor_window_controller()
+      ->SetDisplay(display);
 #endif
 }
 
@@ -129,8 +135,10 @@ void AshNativeCursorManager::SetCursorSet(
     SetCursor(delegate->GetCursor(), delegate);
 
 #if defined(OS_CHROMEOS)
-  Shell::GetInstance()->display_controller()->cursor_window_controller()->
-      SetCursorSet(cursor_set);
+  Shell::GetInstance()
+      ->window_tree_host_manager()
+      ->cursor_window_controller()
+      ->SetCursorSet(cursor_set);
 #endif
 }
 
diff --git a/ash/wm/coordinate_conversion.cc b/ash/wm/coordinate_conversion.cc
index c13ccdc9..c09448c 100644
--- a/ash/wm/coordinate_conversion.cc
+++ b/ash/wm/coordinate_conversion.cc
@@ -4,7 +4,7 @@
 
 #include "ash/wm/coordinate_conversion.h"
 
-#include "ash/display/display_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/shell.h"
 #include "ui/aura/client/screen_position_client.h"
 #include "ui/gfx/display.h"
@@ -21,14 +21,16 @@ aura::Window* GetRootWindowAt(const gfx::Point& point) {
   DCHECK(display.is_valid());
   // TODO(yusukes): Move coordinate_conversion.cc and .h to ui/aura/ once
   // GetRootWindowForDisplayId() is moved to aura::Env.
-  return Shell::GetInstance()->display_controller()->
-      GetRootWindowForDisplayId(display.id());
+  return Shell::GetInstance()
+      ->window_tree_host_manager()
+      ->GetRootWindowForDisplayId(display.id());
 }
 
 aura::Window* GetRootWindowMatching(const gfx::Rect& rect) {
   const gfx::Display& display = Shell::GetScreen()->GetDisplayMatching(rect);
-  return Shell::GetInstance()->display_controller()->
-      GetRootWindowForDisplayId(display.id());
+  return Shell::GetInstance()
+      ->window_tree_host_manager()
+      ->GetRootWindowForDisplayId(display.id());
 }
 
 }  // namespace wm
diff --git a/ash/wm/default_state.cc b/ash/wm/default_state.cc
index 953789e..b5e5f5b 100644
--- a/ash/wm/default_state.cc
+++ b/ash/wm/default_state.cc
@@ -4,7 +4,7 @@
 
 #include "ash/wm/default_state.h"
 
-#include "ash/display/display_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/screen_util.h"
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
@@ -58,10 +58,10 @@ void MoveToDisplayForRestore(WindowState* window_state) {
   if (!display_area.Intersects(restore_bounds)) {
     const gfx::Display& display =
         Shell::GetScreen()->GetDisplayMatching(restore_bounds);
-    DisplayController* display_controller =
-        Shell::GetInstance()->display_controller();
+    WindowTreeHostManager* window_tree_host_manager =
+        Shell::GetInstance()->window_tree_host_manager();
     aura::Window* new_root =
-        display_controller->GetRootWindowForDisplayId(display.id());
+        window_tree_host_manager->GetRootWindowForDisplayId(display.id());
     if (new_root != window_state->window()->GetRootWindow()) {
       aura::Window* new_container =
           Shell::GetContainer(new_root, window_state->window()->parent()->id());
diff --git a/ash/wm/dock/docked_window_resizer.cc b/ash/wm/dock/docked_window_resizer.cc
index 4f92f23..9e4eb2d 100644
--- a/ash/wm/dock/docked_window_resizer.cc
+++ b/ash/wm/dock/docked_window_resizer.cc
@@ -4,7 +4,7 @@
 
 #include "ash/wm/dock/docked_window_resizer.h"
 
-#include "ash/display/display_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/root_window_controller.h"
 #include "ash/screen_util.h"
 #include "ash/shelf/shelf.h"
@@ -40,8 +40,9 @@ DockedWindowLayoutManager* GetDockedLayoutManagerAtPoint(
   gfx::Display display = ScreenUtil::FindDisplayContainingPoint(point);
   if (!display.is_valid())
     return NULL;
-  aura::Window* root = Shell::GetInstance()->display_controller()->
-      GetRootWindowForDisplayId(display.id());
+  aura::Window* root = Shell::GetInstance()
+                           ->window_tree_host_manager()
+                           ->GetRootWindowForDisplayId(display.id());
   aura::Window* dock_container = Shell::GetContainer(
       root, kShellWindowId_DockedContainer);
   return static_cast<DockedWindowLayoutManager*>(
diff --git a/ash/wm/dock/docked_window_resizer_unittest.cc b/ash/wm/dock/docked_window_resizer_unittest.cc
index 6ace192b..a96c262 100644
--- a/ash/wm/dock/docked_window_resizer_unittest.cc
+++ b/ash/wm/dock/docked_window_resizer_unittest.cc
@@ -5,6 +5,7 @@
 #include "ash/wm/dock/docked_window_resizer.h"
 
 #include "ash/ash_switches.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/root_window_controller.h"
 #include "ash/screen_util.h"
 #include "ash/shelf/shelf.h"
@@ -100,8 +101,9 @@ class DockedWindowResizerTest
     } else {
       gfx::Display display =
           Shell::GetScreen()->GetDisplayMatching(bounds);
-      aura::Window* root = ash::Shell::GetInstance()->display_controller()->
-          GetRootWindowForDisplayId(display.id());
+      aura::Window* root = ash::Shell::GetInstance()
+                               ->window_tree_host_manager()
+                               ->GetRootWindowForDisplayId(display.id());
       gfx::Point origin = bounds.origin();
       ::wm::ConvertPointFromScreen(root, &origin);
       window->SetBounds(gfx::Rect(origin, bounds.size()));
diff --git a/ash/wm/gestures/long_press_affordance_handler.cc b/ash/wm/gestures/long_press_affordance_handler.cc
index 11be224..692510f 100644
--- a/ash/wm/gestures/long_press_affordance_handler.cc
+++ b/ash/wm/gestures/long_press_affordance_handler.cc
@@ -4,7 +4,6 @@
 
 #include "ash/wm/gestures/long_press_affordance_handler.h"
 
-#include "ash/display/display_controller.h"
 #include "ash/root_window_controller.h"
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
diff --git a/ash/wm/maximize_mode/maximize_mode_window_state.cc b/ash/wm/maximize_mode/maximize_mode_window_state.cc
index 0590077..e8da85a 100644
--- a/ash/wm/maximize_mode/maximize_mode_window_state.cc
+++ b/ash/wm/maximize_mode/maximize_mode_window_state.cc
@@ -4,7 +4,6 @@
 
 #include "ash/wm/maximize_mode/maximize_mode_window_state.h"
 
-#include "ash/display/display_controller.h"
 #include "ash/screen_util.h"
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
diff --git a/ash/wm/maximize_mode/scoped_disable_internal_mouse_and_keyboard_x11.cc b/ash/wm/maximize_mode/scoped_disable_internal_mouse_and_keyboard_x11.cc
index 22419c9..7704394 100644
--- a/ash/wm/maximize_mode/scoped_disable_internal_mouse_and_keyboard_x11.cc
+++ b/ash/wm/maximize_mode/scoped_disable_internal_mouse_and_keyboard_x11.cc
@@ -8,7 +8,7 @@
 #include <X11/extensions/XInput2.h>
 #include <X11/Xlib.h>
 
-#include "ash/display/display_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/screen_util.h"
 #include "ash/shell.h"
 #include "base/memory/scoped_ptr.h"
@@ -52,8 +52,9 @@ void SetMouseLocationInScreen(const gfx::Point& screen_location) {
       screen_location);
   if (!display.is_valid())
     return;
-  aura::Window* root_window = Shell::GetInstance()->display_controller()->
-      GetRootWindowForDisplayId(display.id());
+  aura::Window* root_window = Shell::GetInstance()
+                                  ->window_tree_host_manager()
+                                  ->GetRootWindowForDisplayId(display.id());
   gfx::Point host_location(screen_location);
   aura::client::ScreenPositionClient* client =
       aura::client::GetScreenPositionClient(root_window);
diff --git a/ash/wm/panels/panel_layout_manager.cc b/ash/wm/panels/panel_layout_manager.cc
index 11f2c1d..8e59a7f 100644
--- a/ash/wm/panels/panel_layout_manager.cc
+++ b/ash/wm/panels/panel_layout_manager.cc
@@ -268,7 +268,7 @@ PanelLayoutManager::PanelLayoutManager(aura::Window* panel_container)
   DCHECK(panel_container);
   aura::client::GetActivationClient(Shell::GetPrimaryRootWindow())->
       AddObserver(this);
-  Shell::GetInstance()->display_controller()->AddObserver(this);
+  Shell::GetInstance()->window_tree_host_manager()->AddObserver(this);
   Shell::GetInstance()->AddShellObserver(this);
 }
 
@@ -290,7 +290,7 @@ void PanelLayoutManager::Shutdown() {
   shelf_ = NULL;
   aura::client::GetActivationClient(Shell::GetPrimaryRootWindow())->
       RemoveObserver(this);
-  Shell::GetInstance()->display_controller()->RemoveObserver(this);
+  Shell::GetInstance()->window_tree_host_manager()->RemoveObserver(this);
   Shell::GetInstance()->RemoveShellObserver(this);
 }
 
@@ -526,7 +526,7 @@ void PanelLayoutManager::OnWindowActivated(
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-// PanelLayoutManager, DisplayController::Observer implementation:
+// PanelLayoutManager, WindowTreeHostManager::Observer implementation:
 
 void PanelLayoutManager::OnDisplayConfigurationChanged() {
   Relayout();
diff --git a/ash/wm/panels/panel_layout_manager.h b/ash/wm/panels/panel_layout_manager.h
index 427e5f1..434506a 100644
--- a/ash/wm/panels/panel_layout_manager.h
+++ b/ash/wm/panels/panel_layout_manager.h
@@ -8,7 +8,7 @@
 #include <list>
 
 #include "ash/ash_export.h"
-#include "ash/display/display_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/shelf/shelf_icon_observer.h"
 #include "ash/shelf/shelf_layout_manager_observer.h"
 #include "ash/shell_observer.h"
@@ -58,7 +58,7 @@ class ASH_EXPORT PanelLayoutManager
       public wm::WindowStateObserver,
       public aura::client::ActivationChangeObserver,
       public keyboard::KeyboardControllerObserver,
-      public DisplayController::Observer,
+      public WindowTreeHostManager::Observer,
       public ShelfLayoutManagerObserver {
  public:
   explicit PanelLayoutManager(aura::Window* panel_container);
@@ -113,7 +113,7 @@ class ASH_EXPORT PanelLayoutManager
       aura::Window* gained_active,
       aura::Window* lost_active) override;
 
-  // Overridden from DisplayController::Observer
+  // Overridden from WindowTreeHostManager::Observer
   void OnDisplayConfigurationChanged() override;
 
   // Overridden from ShelfLayoutManagerObserver
diff --git a/ash/wm/panels/panel_window_resizer.cc b/ash/wm/panels/panel_window_resizer.cc
index a57ac59..57a8de5 100644
--- a/ash/wm/panels/panel_window_resizer.cc
+++ b/ash/wm/panels/panel_window_resizer.cc
@@ -4,7 +4,7 @@
 
 #include "ash/wm/panels/panel_window_resizer.h"
 
-#include "ash/display/display_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/screen_util.h"
 #include "ash/shelf/shelf.h"
 #include "ash/shelf/shelf_types.h"
@@ -70,8 +70,9 @@ void PanelWindowResizer::Drag(const gfx::Point& location, int event_flags) {
     // complete it would begin positioning the panel.
     if (GetTarget()->parent() != panel_container_)
       GetPanelLayoutManager(panel_container_)->FinishDragging();
-    aura::Window* dst_root = Shell::GetInstance()->display_controller()->
-        GetRootWindowForDisplayId(dst_display.id());
+    aura::Window* dst_root = Shell::GetInstance()
+                                 ->window_tree_host_manager()
+                                 ->GetRootWindowForDisplayId(dst_display.id());
     panel_container_ =
         Shell::GetContainer(dst_root, kShellWindowId_PanelContainer);
 
diff --git a/ash/wm/toplevel_window_event_handler.cc b/ash/wm/toplevel_window_event_handler.cc
index 667fc52..884efd4 100644
--- a/ash/wm/toplevel_window_event_handler.cc
+++ b/ash/wm/toplevel_window_event_handler.cc
@@ -166,11 +166,11 @@ ToplevelWindowEventHandler::ToplevelWindowEventHandler()
       in_gesture_drag_(false),
       drag_reverted_(false),
       destroyed_(NULL) {
-  Shell::GetInstance()->display_controller()->AddObserver(this);
+  Shell::GetInstance()->window_tree_host_manager()->AddObserver(this);
 }
 
 ToplevelWindowEventHandler::~ToplevelWindowEventHandler() {
-  Shell::GetInstance()->display_controller()->RemoveObserver(this);
+  Shell::GetInstance()->window_tree_host_manager()->RemoveObserver(this);
   if (destroyed_)
     *destroyed_ = true;
 }
diff --git a/ash/wm/toplevel_window_event_handler.h b/ash/wm/toplevel_window_event_handler.h
index bcaaa91..80ce0f8 100644
--- a/ash/wm/toplevel_window_event_handler.h
+++ b/ash/wm/toplevel_window_event_handler.h
@@ -8,7 +8,7 @@
 #include <set>
 
 #include "ash/ash_export.h"
-#include "ash/display/display_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/wm/wm_types.h"
 #include "base/callback.h"
 #include "base/compiler_specific.h"
@@ -33,7 +33,7 @@ class WindowResizer;
 class ASH_EXPORT ToplevelWindowEventHandler
     : public ui::EventHandler,
       public aura::client::WindowMoveClient,
-      public DisplayController::Observer {
+      public WindowTreeHostManager::Observer {
  public:
   ToplevelWindowEventHandler();
   ~ToplevelWindowEventHandler() override;
@@ -50,7 +50,7 @@ class ASH_EXPORT ToplevelWindowEventHandler
       aura::client::WindowMoveSource move_source) override;
   void EndMoveLoop() override;
 
-  // Overridden form ash::DisplayController::Observer:
+  // Overridden form ash::WindowTreeHostManager::Observer:
   void OnDisplayConfigurationChanging() override;
 
  private:
diff --git a/ash/wm/workspace/workspace_layout_manager.cc b/ash/wm/workspace/workspace_layout_manager.cc
index b8b2f1f..6c8a8ee 100644
--- a/ash/wm/workspace/workspace_layout_manager.cc
+++ b/ash/wm/workspace/workspace_layout_manager.cc
@@ -6,7 +6,6 @@
 
 #include <algorithm>
 
-#include "ash/display/display_controller.h"
 #include "ash/root_window_controller.h"
 #include "ash/screen_util.h"
 #include "ash/session/session_state_delegate.h"
diff --git a/ash/wm/workspace/workspace_window_resizer.cc b/ash/wm/workspace/workspace_window_resizer.cc
index 73ba6fb..2b30dd1 100644
--- a/ash/wm/workspace/workspace_window_resizer.cc
+++ b/ash/wm/workspace/workspace_window_resizer.cc
@@ -9,7 +9,7 @@
 #include <utility>
 #include <vector>
 
-#include "ash/display/display_controller.h"
+#include "ash/display/window_tree_host_manager.h"
 #include "ash/metrics/user_metrics_recorder.h"
 #include "ash/root_window_controller.h"
 #include "ash/screen_util.h"
@@ -383,8 +383,9 @@ void WorkspaceWindowResizer::Drag(const gfx::Point& location_in_parent,
   // Track the last screen that the pointer was on to keep the snap phantom
   // window there.
   if (display.is_valid()) {
-    root = Shell::GetInstance()->display_controller()->
-        GetRootWindowForDisplayId(display.id());
+    root = Shell::GetInstance()
+               ->window_tree_host_manager()
+               ->GetRootWindowForDisplayId(display.id());
   }
   if (!attached_windows_.empty())
     LayoutAttachedWindows(&bounds);