Enables storing shelf's auto_hide_behavior and alignment per display.

BUG=165419
TEST=on a dev-mode device, change the launcher's auto-hide behavior and see how it's stored in Preferences

Review URL: https://codereview.chromium.org/11570017

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@173508 0039d316-1c4b-4281-b951-d872f2087c98

11 files changed, 236 insertions, 88 deletions

diff --git a/ash/shell.cc b/ash/shell.cc
index 65ba167..84a1b41 100644
--- a/ash/shell.cc
+++ b/ash/shell.cc
@@ -727,8 +727,10 @@ ShelfAutoHideBehavior Shell::GetShelfAutoHideBehavior(
 
 void Shell::SetShelfAlignment(ShelfAlignment alignment,
                               aura::RootWindow* root_window) {
-  if (GetRootWindowController(root_window)->SetShelfAlignment(alignment))
-    FOR_EACH_OBSERVER(ShellObserver, observers_, OnShelfAlignmentChanged());
+  if (GetRootWindowController(root_window)->SetShelfAlignment(alignment)) {
+    FOR_EACH_OBSERVER(
+        ShellObserver, observers_, OnShelfAlignmentChanged(root_window));
+  }
 }
 
 ShelfAlignment Shell::GetShelfAlignment(aura::RootWindow* root_window) {
diff --git a/ash/shell_observer.h b/ash/shell_observer.h
index 6cbeaa7..0bdd934 100644
--- a/ash/shell_observer.h
+++ b/ash/shell_observer.h
@@ -8,6 +8,10 @@
 #include "ash/ash_export.h"
 #include "ash/system/user/login_status.h"
 
+namespace aura {
+class RootWindow;
+}
+
 namespace ash {
 
 class ASH_EXPORT ShellObserver {
@@ -25,8 +29,8 @@ class ASH_EXPORT ShellObserver {
   // unlocked.
   virtual void OnLockStateChanged(bool locked) {}
 
-  // Invoked when the shelf alignment is changed.
-  virtual void OnShelfAlignmentChanged() {}
+  // Invoked when the shelf alignment in |root_window| is changed.
+  virtual void OnShelfAlignmentChanged(aura::RootWindow* root_window) {}
 
  protected:
   virtual ~ShellObserver() {}
diff --git a/ash/wm/app_list_controller.cc b/ash/wm/app_list_controller.cc
index bcc85e5..3bfe4ca 100644
--- a/ash/wm/app_list_controller.cc
+++ b/ash/wm/app_list_controller.cc
@@ -285,7 +285,7 @@ void AppListController::OnWidgetClosing(views::Widget* widget) {
 
 ////////////////////////////////////////////////////////////////////////////////
 // AppListController, ShellObserver implementation:
-void AppListController::OnShelfAlignmentChanged() {
+void AppListController::OnShelfAlignmentChanged(aura::RootWindow* root_window) {
   if (view_) {
     view_->SetBubbleArrowLocation(GetBubbleArrowLocation(
         view_->GetWidget()->GetNativeView()));
diff --git a/ash/wm/app_list_controller.h b/ash/wm/app_list_controller.h
index 9111370..f396052 100644
--- a/ash/wm/app_list_controller.h
+++ b/ash/wm/app_list_controller.h
@@ -95,7 +95,7 @@ class AppListController : public ui::EventHandler,
   virtual void OnWidgetClosing(views::Widget* widget) OVERRIDE;
 
   // ShellObserver overrides:
-  virtual void OnShelfAlignmentChanged() OVERRIDE;
+  virtual void OnShelfAlignmentChanged(aura::RootWindow* root_window) OVERRIDE;
 
   // LauncherIconObserver overrides:
   virtual void OnLauncherIconPositionsChanged() OVERRIDE;
diff --git a/chrome/browser/ui/ash/chrome_launcher_prefs.cc b/chrome/browser/ui/ash/chrome_launcher_prefs.cc
index 15b6d7e..985e3e5 100644
--- a/chrome/browser/ui/ash/chrome_launcher_prefs.cc
+++ b/chrome/browser/ui/ash/chrome_launcher_prefs.cc
@@ -62,6 +62,8 @@ void RegisterChromeLauncherUserPrefs(PrefService* user_prefs) {
   user_prefs->RegisterBooleanPref(prefs::kShowLogoutButtonInTray,
                                   false,
                                   PrefService::UNSYNCABLE_PREF);
+  user_prefs->RegisterDictionaryPref(prefs::kShelfPreferences,
+                                     PrefService::UNSYNCABLE_PREF);
 }
 
 base::DictionaryValue* CreateAppDict(const std::string& app_id) {
diff --git a/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_app.cc b/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_app.cc
index 3e5262e..ebc70b4 100644
--- a/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_app.cc
+++ b/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_app.cc
@@ -10,6 +10,7 @@
 #include "ash/shell.h"
 #include "ash/wm/window_util.h"
 #include "base/command_line.h"
+#include "base/string_number_conversions.h"
 #include "base/values.h"
 #include "chrome/browser/defaults.h"
 #include "chrome/browser/extensions/extension_service.h"
@@ -44,6 +45,7 @@
 #include "content/public/browser/web_contents.h"
 #include "extensions/common/url_pattern.h"
 #include "grit/theme_resources.h"
+#include "ui/aura/root_window.h"
 #include "ui/aura/window.h"
 
 using content::WebContents;
@@ -118,13 +120,67 @@ class AppShortcutLauncherItemController : public LauncherItemController {
   DISALLOW_COPY_AND_ASSIGN(AppShortcutLauncherItemController);
 };
 
-// If the value of the pref at |local_path is not empty, it is returned
-// otherwise the value of the pref at |synced_path| is returned.
-std::string GetLocalOrRemotePref(PrefService* pref_service,
+std::string GetPrefKeyForRootWindow(aura::RootWindow* root_window) {
+  gfx::Display display = gfx::Screen::GetScreenFor(
+      root_window)->GetDisplayNearestWindow(root_window);
+  DCHECK(display.is_valid());
+
+  return base::Int64ToString(display.id());
+}
+
+void UpdatePerDisplayPref(PrefService* pref_service,
+                          aura::RootWindow* root_window,
+                          const char* pref_key,
+                          const std::string& value) {
+  std::string key = GetPrefKeyForRootWindow(root_window);
+  if (key.empty())
+    return;
+
+  DictionaryPrefUpdate update(pref_service, prefs::kShelfPreferences);
+  base::DictionaryValue* shelf_prefs = update.Get();
+  base::DictionaryValue* prefs = NULL;
+  if (!shelf_prefs->GetDictionary(key, &prefs)) {
+    prefs = new base::DictionaryValue();
+    shelf_prefs->Set(key, prefs);
+  }
+  prefs->SetStringWithoutPathExpansion(pref_key, value);
+}
+
+// Returns a pref value in |pref_service| for the display of |root_window|. The
+// pref value is stored in |local_path| and |path|, but |pref_service| may have
+// per-display preferences and the value can be specified by policy. Here is
+// the priority:
+//  * A value managed by policy. This is a single value that applies to all
+//    displays.
+//  * A user-set value for the specified display.
+//  * A user-set value in |local_path| or |path|. |local_path| is preferred. See
+//    comment in |kShelfAlignment| as to why we consider two prefs and why
+//    |local_path| is preferred.
+//  * A value recommended by policy. This is a single value that applies to all
+//    root windows.
+std::string GetPrefForRootWindow(PrefService* pref_service,
+                                 aura::RootWindow* root_window,
                                  const char* local_path,
-                                 const char* synced_path) {
+                                 const char* path) {
+  const PrefService::Preference* local_pref =
+      pref_service->FindPreference(local_path);
   const std::string value(pref_service->GetString(local_path));
-  return value.empty() ? pref_service->GetString(synced_path) : value;
+  if (local_pref->IsManaged())
+    return value;
+
+  std::string pref_key = GetPrefKeyForRootWindow(root_window);
+  if (!pref_key.empty()) {
+    const base::DictionaryValue* shelf_prefs = pref_service->GetDictionary(
+        prefs::kShelfPreferences);
+    const base::DictionaryValue* display_pref = NULL;
+    std::string per_display_value;
+    if (shelf_prefs->GetDictionary(pref_key, &display_pref) &&
+        display_pref->GetString(path, &per_display_value)) {
+      return per_display_value;
+    }
+  }
+
+  return value;
 }
 
 // If prefs have synced and no user-set value exists at |local_path|, the value
@@ -563,11 +619,10 @@ bool ChromeLauncherControllerPerApp::CanPin() const {
 ash::ShelfAutoHideBehavior
     ChromeLauncherControllerPerApp::GetShelfAutoHideBehavior(
         aura::RootWindow* root_window) const {
-  // TODO(oshima): Support multiple launchers.
-
   // See comment in |kShelfAlignment| as to why we consider two prefs.
   const std::string behavior_value(
-      GetLocalOrRemotePref(profile_->GetPrefs(),
+      GetPrefForRootWindow(profile_->GetPrefs(),
+                           root_window,
                            prefs::kShelfAutoHideBehaviorLocal,
                            prefs::kShelfAutoHideBehavior));
 
@@ -582,7 +637,6 @@ ash::ShelfAutoHideBehavior
 
 bool ChromeLauncherControllerPerApp::CanUserModifyShelfAutoHideBehavior(
     aura::RootWindow* root_window) const {
-  // TODO(oshima): Support multiple launchers.
   return profile_->GetPrefs()->
       FindPreference(prefs::kShelfAutoHideBehaviorLocal)->IsUserModifiable();
 }
@@ -797,11 +851,10 @@ void ChromeLauncherControllerPerApp::Observe(
   }
 }
 
-void ChromeLauncherControllerPerApp::OnShelfAlignmentChanged() {
+void ChromeLauncherControllerPerApp::OnShelfAlignmentChanged(
+    aura::RootWindow* root_window) {
   const char* pref_value = NULL;
-  // TODO(oshima): Support multiple displays.
-  switch (ash::Shell::GetInstance()->GetShelfAlignment(
-      ash::Shell::GetPrimaryRootWindow())) {
+  switch (ash::Shell::GetInstance()->GetShelfAlignment(root_window)) {
     case ash::SHELF_ALIGNMENT_BOTTOM:
       pref_value = ash::kShelfAlignmentBottom;
       break;
@@ -812,9 +865,15 @@ void ChromeLauncherControllerPerApp::OnShelfAlignmentChanged() {
       pref_value = ash::kShelfAlignmentRight;
       break;
   }
-  // See comment in |kShelfAlignment| about why we have two prefs here.
-  profile_->GetPrefs()->SetString(prefs::kShelfAlignmentLocal, pref_value);
-  profile_->GetPrefs()->SetString(prefs::kShelfAlignment, pref_value);
+
+  UpdatePerDisplayPref(
+      profile_->GetPrefs(), root_window, prefs::kShelfAlignment, pref_value);
+
+  if (root_window == ash::Shell::GetPrimaryRootWindow()) {
+    // See comment in |kShelfAlignment| about why we have two prefs here.
+    profile_->GetPrefs()->SetString(prefs::kShelfAlignmentLocal, pref_value);
+    profile_->GetPrefs()->SetString(prefs::kShelfAlignment, pref_value);
+  }
 }
 
 void ChromeLauncherControllerPerApp::OnIsSyncingChanged() {
@@ -989,10 +1048,6 @@ void ChromeLauncherControllerPerApp::UpdateAppLaunchersFromPref() {
 void ChromeLauncherControllerPerApp::SetShelfAutoHideBehaviorPrefs(
     ash::ShelfAutoHideBehavior behavior,
     aura::RootWindow* root_window) {
-  // TODO(oshima): Support multiple launchers.
-  if (root_window != ash::Shell::GetPrimaryRootWindow())
-    return;
-
   const char* value = NULL;
   switch (behavior) {
     case ash::SHELF_AUTO_HIDE_BEHAVIOR_ALWAYS:
@@ -1002,16 +1057,24 @@ void ChromeLauncherControllerPerApp::SetShelfAutoHideBehaviorPrefs(
       value = ash::kShelfAutoHideBehaviorNever;
       break;
   }
-  // See comment in |kShelfAlignment| about why we have two prefs here.
-  profile_->GetPrefs()->SetString(prefs::kShelfAutoHideBehaviorLocal, value);
-  profile_->GetPrefs()->SetString(prefs::kShelfAutoHideBehavior, value);
+
+  UpdatePerDisplayPref(
+      profile_->GetPrefs(), root_window, prefs::kShelfAutoHideBehavior, value);
+
+  if (root_window == ash::Shell::GetPrimaryRootWindow()) {
+    // See comment in |kShelfAlignment| about why we have two prefs here.
+    profile_->GetPrefs()->SetString(prefs::kShelfAutoHideBehaviorLocal, value);
+    profile_->GetPrefs()->SetString(prefs::kShelfAutoHideBehavior, value);
+  }
 }
 
 void ChromeLauncherControllerPerApp::SetShelfAutoHideBehaviorFromPrefs() {
-  // TODO(oshima): Support multiple displays.
-  aura::RootWindow* root_window = ash::Shell::GetPrimaryRootWindow();
-  ash::Shell::GetInstance()->SetShelfAutoHideBehavior(
-      GetShelfAutoHideBehavior(root_window), root_window);
+  ash::Shell::RootWindowList root_windows = ash::Shell::GetAllRootWindows();
+  for (ash::Shell::RootWindowList::const_iterator iter = root_windows.begin();
+       iter != root_windows.end(); ++iter) {
+    ash::Shell::GetInstance()->SetShelfAutoHideBehavior(
+        GetShelfAutoHideBehavior(*iter), *iter);
+  }
 }
 
 void ChromeLauncherControllerPerApp::SetShelfAlignmentFromPrefs() {
@@ -1019,19 +1082,22 @@ void ChromeLauncherControllerPerApp::SetShelfAlignmentFromPrefs() {
           switches::kShowLauncherAlignmentMenu))
     return;
 
-  // See comment in |kShelfAlignment| as to why we consider two prefs.
-  const std::string alignment_value(
-      GetLocalOrRemotePref(profile_->GetPrefs(),
-                           prefs::kShelfAlignmentLocal,
-                           prefs::kShelfAlignment));
-  ash::ShelfAlignment alignment = ash::SHELF_ALIGNMENT_BOTTOM;
-  if (alignment_value == ash::kShelfAlignmentLeft)
-    alignment = ash::SHELF_ALIGNMENT_LEFT;
-  else if (alignment_value == ash::kShelfAlignmentRight)
-    alignment = ash::SHELF_ALIGNMENT_RIGHT;
-  // TODO(oshima): Support multiple displays.
-  ash::Shell::GetInstance()->SetShelfAlignment(
-      alignment, ash::Shell::GetPrimaryRootWindow());
+  ash::Shell::RootWindowList root_windows = ash::Shell::GetAllRootWindows();
+  for (ash::Shell::RootWindowList::const_iterator iter = root_windows.begin();
+       iter != root_windows.end(); ++iter) {
+    // See comment in |kShelfAlignment| as to why we consider two prefs.
+    const std::string alignment_value(
+        GetPrefForRootWindow(profile_->GetPrefs(),
+                             *iter,
+                             prefs::kShelfAlignmentLocal,
+                             prefs::kShelfAlignment));
+    ash::ShelfAlignment alignment = ash::SHELF_ALIGNMENT_BOTTOM;
+    if (alignment_value == ash::kShelfAlignmentLeft)
+      alignment = ash::SHELF_ALIGNMENT_LEFT;
+    else if (alignment_value == ash::kShelfAlignmentRight)
+      alignment = ash::SHELF_ALIGNMENT_RIGHT;
+    ash::Shell::GetInstance()->SetShelfAlignment(alignment, *iter);
+  }
 }
 
 WebContents* ChromeLauncherControllerPerApp::GetLastActiveWebContents(
diff --git a/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_app.h b/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_app.h
index b63f4f4..7288355 100644
--- a/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_app.h
+++ b/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_app.h
@@ -248,7 +248,7 @@ class ChromeLauncherControllerPerApp
                        const content::NotificationDetails& details) OVERRIDE;
 
   // Overridden from ash::ShellObserver:
-  virtual void OnShelfAlignmentChanged() OVERRIDE;
+  virtual void OnShelfAlignmentChanged(aura::RootWindow* root_window) OVERRIDE;
 
   // Overridden from PrefServiceObserver:
   virtual void OnIsSyncingChanged() OVERRIDE;
diff --git a/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_browser.cc b/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_browser.cc
index a0a5bb1..3691d95 100644
--- a/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_browser.cc
+++ b/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_browser.cc
@@ -10,6 +10,7 @@
 #include "ash/shell.h"
 #include "ash/wm/window_util.h"
 #include "base/command_line.h"
+#include "base/string_number_conversions.h"
 #include "base/values.h"
 #include "chrome/browser/defaults.h"
 #include "chrome/browser/extensions/extension_service.h"
@@ -44,6 +45,7 @@
 #include "content/public/browser/web_contents.h"
 #include "extensions/common/url_pattern.h"
 #include "grit/theme_resources.h"
+#include "ui/aura/root_window.h"
 #include "ui/aura/window.h"
 
 using content::WebContents;
@@ -119,13 +121,67 @@ class AppShortcutLauncherItemController : public LauncherItemController {
   DISALLOW_COPY_AND_ASSIGN(AppShortcutLauncherItemController);
 };
 
-// If the value of the pref at |local_path is not empty, it is returned
-// otherwise the value of the pref at |synced_path| is returned.
-std::string GetLocalOrRemotePref(PrefService* pref_service,
+std::string GetPrefKeyForRootWindow(aura::RootWindow* root_window) {
+  gfx::Display display = gfx::Screen::GetScreenFor(
+      root_window)->GetDisplayNearestWindow(root_window);
+  DCHECK(display.is_valid());
+
+  return base::Int64ToString(display.id());
+}
+
+void UpdatePerDisplayPref(PrefService* pref_service,
+                          aura::RootWindow* root_window,
+                          const char* pref_key,
+                          const std::string& value) {
+  std::string key = GetPrefKeyForRootWindow(root_window);
+  if (key.empty())
+    return;
+
+  DictionaryPrefUpdate update(pref_service, prefs::kShelfPreferences);
+  base::DictionaryValue* shelf_prefs = update.Get();
+  base::DictionaryValue* prefs = NULL;
+  if (!shelf_prefs->GetDictionary(key, &prefs)) {
+    prefs = new base::DictionaryValue();
+    shelf_prefs->Set(key, prefs);
+  }
+  prefs->SetStringWithoutPathExpansion(pref_key, value);
+}
+
+// Returns a pref value in |pref_service| for the display of |root_window|. The
+// pref value is stored in |local_path| and |path|, but |pref_service| may have
+// per-display preferences and the value can be specified by policy. Here is
+// the priority:
+//  * A value managed by policy. This is a single value that applies to all
+//    displays.
+//  * A user-set value for the specified display.
+//  * A user-set value in |local_path| or |path|. |local_path| is preferred. See
+//    comment in |kShelfAlignment| as to why we consider two prefs and why
+//    |local_path| is preferred.
+//  * A value recommended by policy. This is a single value that applies to all
+//    root windows.
+std::string GetPrefForRootWindow(PrefService* pref_service,
+                                 aura::RootWindow* root_window,
                                  const char* local_path,
-                                 const char* synced_path) {
+                                 const char* path) {
+  const PrefService::Preference* local_pref =
+      pref_service->FindPreference(local_path);
   const std::string value(pref_service->GetString(local_path));
-  return value.empty() ? pref_service->GetString(synced_path) : value;
+  if (local_pref->IsManaged())
+    return value;
+
+  std::string pref_key = GetPrefKeyForRootWindow(root_window);
+  if (!pref_key.empty()) {
+    const base::DictionaryValue* shelf_prefs = pref_service->GetDictionary(
+        prefs::kShelfPreferences);
+    const base::DictionaryValue* display_pref = NULL;
+    std::string per_display_value;
+    if (shelf_prefs->GetDictionary(pref_key, &display_pref) &&
+        display_pref->GetString(path, &per_display_value)) {
+      return per_display_value;
+    }
+  }
+
+  return value;
 }
 
 // If prefs have synced and no user-set value exists at |local_path|, the value
@@ -570,11 +626,10 @@ bool ChromeLauncherControllerPerBrowser::CanPin() const {
 ash::ShelfAutoHideBehavior
     ChromeLauncherControllerPerBrowser::GetShelfAutoHideBehavior(
         aura::RootWindow* root_window) const {
-  // TODO(oshima): Support multiple launchers.
-
   // See comment in |kShelfAlignment| as to why we consider two prefs.
   const std::string behavior_value(
-      GetLocalOrRemotePref(profile_->GetPrefs(),
+      GetPrefForRootWindow(profile_->GetPrefs(),
+                           root_window,
                            prefs::kShelfAutoHideBehaviorLocal,
                            prefs::kShelfAutoHideBehavior));
 
@@ -589,7 +644,6 @@ ash::ShelfAutoHideBehavior
 
 bool ChromeLauncherControllerPerBrowser::CanUserModifyShelfAutoHideBehavior(
     aura::RootWindow* root_window) const {
-  // TODO(oshima): Support multiple launchers.
   return profile_->GetPrefs()->
       FindPreference(prefs::kShelfAutoHideBehaviorLocal)->IsUserModifiable();
 }
@@ -805,11 +859,10 @@ void ChromeLauncherControllerPerBrowser::Observe(
   }
 }
 
-void ChromeLauncherControllerPerBrowser::OnShelfAlignmentChanged() {
+void ChromeLauncherControllerPerBrowser::OnShelfAlignmentChanged(
+    aura::RootWindow* root_window) {
   const char* pref_value = NULL;
-  // TODO(oshima): Support multiple displays.
-  switch (ash::Shell::GetInstance()->GetShelfAlignment(
-      ash::Shell::GetPrimaryRootWindow())) {
+  switch (ash::Shell::GetInstance()->GetShelfAlignment(root_window)) {
     case ash::SHELF_ALIGNMENT_BOTTOM:
       pref_value = ash::kShelfAlignmentBottom;
       break;
@@ -820,9 +873,15 @@ void ChromeLauncherControllerPerBrowser::OnShelfAlignmentChanged() {
       pref_value = ash::kShelfAlignmentRight;
       break;
   }
-  // See comment in |kShelfAlignment| about why we have two prefs here.
-  profile_->GetPrefs()->SetString(prefs::kShelfAlignmentLocal, pref_value);
-  profile_->GetPrefs()->SetString(prefs::kShelfAlignment, pref_value);
+
+  UpdatePerDisplayPref(
+      profile_->GetPrefs(), root_window, prefs::kShelfAlignment, pref_value);
+
+  if (root_window == ash::Shell::GetPrimaryRootWindow()) {
+    // See comment in |kShelfAlignment| about why we have two prefs here.
+    profile_->GetPrefs()->SetString(prefs::kShelfAlignmentLocal, pref_value);
+    profile_->GetPrefs()->SetString(prefs::kShelfAlignment, pref_value);
+  }
 }
 
 void ChromeLauncherControllerPerBrowser::OnIsSyncingChanged() {
@@ -999,10 +1058,6 @@ void ChromeLauncherControllerPerBrowser::UpdateAppLaunchersFromPref() {
 void ChromeLauncherControllerPerBrowser::SetShelfAutoHideBehaviorPrefs(
     ash::ShelfAutoHideBehavior behavior,
     aura::RootWindow* root_window) {
-  // TODO(oshima): Support multiple launchers.
-  if (root_window != ash::Shell::GetPrimaryRootWindow())
-    return;
-
   const char* value = NULL;
   switch (behavior) {
     case ash::SHELF_AUTO_HIDE_BEHAVIOR_ALWAYS:
@@ -1012,16 +1067,24 @@ void ChromeLauncherControllerPerBrowser::SetShelfAutoHideBehaviorPrefs(
       value = ash::kShelfAutoHideBehaviorNever;
       break;
   }
-  // See comment in |kShelfAlignment| about why we have two prefs here.
-  profile_->GetPrefs()->SetString(prefs::kShelfAutoHideBehaviorLocal, value);
-  profile_->GetPrefs()->SetString(prefs::kShelfAutoHideBehavior, value);
+
+  UpdatePerDisplayPref(
+      profile_->GetPrefs(), root_window, prefs::kShelfAutoHideBehavior, value);
+
+  if (root_window != ash::Shell::GetPrimaryRootWindow()) {
+    // See comment in |kShelfAlignment| about why we have two prefs here.
+    profile_->GetPrefs()->SetString(prefs::kShelfAutoHideBehaviorLocal, value);
+    profile_->GetPrefs()->SetString(prefs::kShelfAutoHideBehavior, value);
+  }
 }
 
 void ChromeLauncherControllerPerBrowser::SetShelfAutoHideBehaviorFromPrefs() {
-  // TODO(oshima): Support multiple displays.
-  aura::RootWindow* root_window = ash::Shell::GetPrimaryRootWindow();
-  ash::Shell::GetInstance()->SetShelfAutoHideBehavior(
-      GetShelfAutoHideBehavior(root_window), root_window);
+  ash::Shell::RootWindowList root_windows = ash::Shell::GetAllRootWindows();
+  for (ash::Shell::RootWindowList::const_iterator iter = root_windows.begin();
+       iter != root_windows.end(); ++iter) {
+    ash::Shell::GetInstance()->SetShelfAutoHideBehavior(
+        GetShelfAutoHideBehavior(*iter), *iter);
+  }
 }
 
 void ChromeLauncherControllerPerBrowser::SetShelfAlignmentFromPrefs() {
@@ -1029,19 +1092,22 @@ void ChromeLauncherControllerPerBrowser::SetShelfAlignmentFromPrefs() {
           switches::kShowLauncherAlignmentMenu))
     return;
 
-  // See comment in |kShelfAlignment| as to why we consider two prefs.
-  const std::string alignment_value(
-      GetLocalOrRemotePref(profile_->GetPrefs(),
-                           prefs::kShelfAlignmentLocal,
-                           prefs::kShelfAlignment));
-  ash::ShelfAlignment alignment = ash::SHELF_ALIGNMENT_BOTTOM;
-  if (alignment_value == ash::kShelfAlignmentLeft)
-    alignment = ash::SHELF_ALIGNMENT_LEFT;
-  else if (alignment_value == ash::kShelfAlignmentRight)
-    alignment = ash::SHELF_ALIGNMENT_RIGHT;
-  // TODO(oshima): Support multiple displays.
-  ash::Shell::GetInstance()->SetShelfAlignment(
-      alignment, ash::Shell::GetPrimaryRootWindow());
+  ash::Shell::RootWindowList root_windows = ash::Shell::GetAllRootWindows();
+  for (ash::Shell::RootWindowList::const_iterator iter = root_windows.begin();
+       iter != root_windows.end(); ++iter) {
+    // See comment in |kShelfAlignment| as to why we consider two prefs.
+    const std::string alignment_value(
+        GetPrefForRootWindow(profile_->GetPrefs(),
+                             *iter,
+                             prefs::kShelfAlignmentLocal,
+                             prefs::kShelfAlignment));
+    ash::ShelfAlignment alignment = ash::SHELF_ALIGNMENT_BOTTOM;
+    if (alignment_value == ash::kShelfAlignmentLeft)
+      alignment = ash::SHELF_ALIGNMENT_LEFT;
+    else if (alignment_value == ash::kShelfAlignmentRight)
+      alignment = ash::SHELF_ALIGNMENT_RIGHT;
+    ash::Shell::GetInstance()->SetShelfAlignment(alignment, *iter);
+  }
 }
 
 WebContents* ChromeLauncherControllerPerBrowser::GetLastActiveWebContents(
diff --git a/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_browser.h b/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_browser.h
index e30c682..e961afc 100644
--- a/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_browser.h
+++ b/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_browser.h
@@ -250,7 +250,7 @@ class ChromeLauncherControllerPerBrowser
                        const content::NotificationDetails& details) OVERRIDE;
 
   // Overridden from ash::ShellObserver:
-  virtual void OnShelfAlignmentChanged() OVERRIDE;
+  virtual void OnShelfAlignmentChanged(aura::RootWindow* root_window) OVERRIDE;
 
   // Overridden from PrefServiceObserver:
   virtual void OnIsSyncingChanged() OVERRIDE;
diff --git a/chrome/common/pref_names.cc b/chrome/common/pref_names.cc
index c20b9ba..7bc0ca6 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -2103,6 +2103,8 @@ const char kMediaGalleriesRememberedGalleries[] =
 // set its value is set from the synced value (once prefs have been
 // synced). This gives a per-machine setting that is initialized from the last
 // set value.
+// These values are default on the machine but can be overridden by per-display
+// values in kShelfPreferences (unless overridden by managed policy).
 // String value corresponding to ash::Shell::ShelfAlignment.
 const char kShelfAlignment[] = "shelf_alignment";
 const char kShelfAlignmentLocal[] = "shelf_alignment_local";
@@ -2112,6 +2114,11 @@ const char kShelfAutoHideBehaviorLocal[] = "auto_hide_behavior_local";
 const char kPinnedLauncherApps[] = "pinned_launcher_apps";
 // Boolean value indicating whether to show a logout button in the ash tray.
 const char kShowLogoutButtonInTray[] = "show_logout_button_in_tray";
+// Dictionary value that holds per-display preference of shelf alignment and
+// auto-hide behavior. Key of the dictionary is the id of the display, and
+// its value is a dictionary whose keys are kShelfAlignment and
+// kShelfAutoHideBehavior.
+const char kShelfPreferences[] = "shelf_preferences";
 
 const char kFlingVelocityCap[] = "gesture.fling_velocity_cap";
 const char kLongPressTimeInSeconds[] =
diff --git a/chrome/common/pref_names.h b/chrome/common/pref_names.h
index 572e06a..c2a6648 100644
--- a/chrome/common/pref_names.h
+++ b/chrome/common/pref_names.h
@@ -766,6 +766,7 @@ extern const char kShelfAutoHideBehavior[];
 extern const char kShelfAutoHideBehaviorLocal[];
 extern const char kPinnedLauncherApps[];
 extern const char kShowLogoutButtonInTray[];
+extern const char kShelfPreferences[];
 
 extern const char kFlingVelocityCap[];
 extern const char kLongPressTimeInSeconds[];