Temporarily remember the primary root window while replacing the display.

|root_windows_| map becomes empty while replacing display.
This CL remembers the primary root window temporarily and
use it when the display is added.

This is a bit ugly but less risky to merge to 25 branch.
For 26, I'll refactor and add "replace" protocol to
DisplayObserver.

BUG=166673
TEST=covered by test

Review URL: https://chromiumcodereview.appspot.com/11644012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@174008 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 46 insertions, 8 deletions

diff --git a/ash/display/display_controller.cc b/ash/display/display_controller.cc
index 2fce25a..940ce88 100644
--- a/ash/display/display_controller.cc
+++ b/ash/display/display_controller.cc
@@ -161,7 +161,8 @@ void DisplayLayout::RegisterJSONConverter(
 }
 
 DisplayController::DisplayController()
-    : desired_primary_display_id_(gfx::Display::kInvalidDisplayID) {
+    : desired_primary_display_id_(gfx::Display::kInvalidDisplayID),
+      primary_root_window_for_replace_(NULL) {
   // Reset primary display to make sure that tests don't use
   // stale display info from previous tests.
   primary_display_id = gfx::Display::kInvalidDisplayID;
@@ -467,14 +468,23 @@ void DisplayController::OnDisplayBoundsChanged(const gfx::Display& display) {
 }
 
 void DisplayController::OnDisplayAdded(const gfx::Display& display) {
-  DCHECK(!root_windows_.empty());
   NotifyDisplayConfigurationChanging();
-  aura::RootWindow* root = AddRootWindowForDisplay(display);
-  UpdateDisplayBoundsForLayout();
-  if (desired_primary_display_id_ == display.id())
-    SetPrimaryDisplay(display);
-
-  Shell::GetInstance()->InitRootWindowForSecondaryDisplay(root);
+  if (primary_root_window_for_replace_) {
+    DCHECK(root_windows_.empty());
+    primary_display_id = display.id();
+    root_windows_[display.id()] = primary_root_window_for_replace_;
+    primary_root_window_for_replace_->SetProperty(
+        internal::kDisplayIdKey, display.id());
+    primary_root_window_for_replace_ = NULL;
+    UpdateDisplayBoundsForLayout();
+  } else {
+    DCHECK(!root_windows_.empty());
+    aura::RootWindow* root = AddRootWindowForDisplay(display);
+    UpdateDisplayBoundsForLayout();
+    if (desired_primary_display_id_ == display.id())
+      SetPrimaryDisplay(display);
+    Shell::GetInstance()->InitRootWindowForSecondaryDisplay(root);
+  }
 }
 
 void DisplayController::OnDisplayRemoved(const gfx::Display& display) {
@@ -489,6 +499,13 @@ void DisplayController::OnDisplayRemoved(const gfx::Display& display) {
   // When the primary root window's display is removed, move the primary
   // root to the other display.
   if (primary_display_id == display.id()) {
+    // Temporarily store the primary root window in
+    // |primary_root_window_for_replace_| when replacing the display.
+    if (root_windows_.size() == 0) {
+      primary_display_id = gfx::Display::kInvalidDisplayID;
+      primary_root_window_for_replace_ = root_to_delete;
+      return;
+    }
     DCHECK_EQ(1U, root_windows_.size());
     primary_display_id = GetSecondaryDisplay()->id();
     aura::RootWindow* primary_root = root_to_delete;
diff --git a/ash/display/display_controller.h b/ash/display/display_controller.h
index 67df6d3..22d92bd 100644
--- a/ash/display/display_controller.h
+++ b/ash/display/display_controller.h
@@ -181,6 +181,10 @@ class ASH_EXPORT DisplayController : public gfx::DisplayObserver {
 
   ObserverList<Observer> observers_;
 
+  // Store the primary root window temporarily while replacing
+  // display.
+  aura::RootWindow* primary_root_window_for_replace_;
+
   DISALLOW_COPY_AND_ASSIGN(DisplayController);
 };
 
diff --git a/ash/display/display_manager_unittest.cc b/ash/display/display_manager_unittest.cc
index ddd20cf..b43944b 100644
--- a/ash/display/display_manager_unittest.cc
+++ b/ash/display/display_manager_unittest.cc
@@ -392,6 +392,23 @@ TEST_F(DisplayManagerTest, TestNativeDisplaysChanged) {
   EXPECT_EQ(2U, display_manager()->GetNumDisplays());
 }
 
+TEST_F(DisplayManagerTest, TestNativeDisplaysChangedNoInternal) {
+  EXPECT_EQ(1U, display_manager()->GetNumDisplays());
+
+  // Don't change the display info if all displays are disconnected.
+  std::vector<gfx::Display> displays;
+  display_manager()->OnNativeDisplaysChanged(displays);
+  EXPECT_EQ(1U, display_manager()->GetNumDisplays());
+
+  // Connect another display which will become primary.
+  const gfx::Display external_display(10, gfx::Rect(1, 1, 100, 100));
+  displays.push_back(external_display);
+  display_manager()->OnNativeDisplaysChanged(displays);
+  EXPECT_EQ(1U, display_manager()->GetNumDisplays());
+  EXPECT_EQ("1,1 100x100",
+            FindDisplayForId(10).bounds_in_pixel().ToString());
+}
+
 TEST_F(DisplayManagerTest, EnsurePointerInDisplays) {
   UpdateDisplay("200x200,300x300");
   Shell::RootWindowList root_windows = Shell::GetAllRootWindows();