Create RootWindowTransformer after root window's bounds and scale factor are updated.

ash/display/display_controller_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // 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_info.h"
 #include "ash/display/display_manager.h"
 #include "ash/launcher/launcher.h"
 #include "ash/screen_ash.h"
@@ skipping 735 matching lines @@
   EXPECT_EQ("5,15", event_handler.GetLocationAndReset());
 
   display_controller->ClearCustomOverscanInsets(display1.id());
   EXPECT_EQ("0,0 120x200", root_windows[0]->bounds().ToString());
   EXPECT_EQ("120,0 150x200",
             ScreenAsh::GetSecondaryDisplay().bounds().ToString());
 
   generator.MoveMouseToInHost(30, 20);
   EXPECT_EQ("30,20", event_handler.GetLocationAndReset());
 
+
+  // Make sure the root window transformer uses correct scale
+  // factor when swapping display. Test crbug.com/253690.
+  UpdateDisplay("400x300*2,600x400/o");
+  root_windows = Shell::GetAllRootWindows();
+  gfx::Point point;
+  Shell::GetAllRootWindows()[1]->GetRootTransform().TransformPoint(point);
+  EXPECT_EQ("15,10", point.ToString());
+
+  display_controller->SwapPrimaryDisplay();
+  point.SetPoint(0, 0);
+  Shell::GetAllRootWindows()[1]->GetRootTransform().TransformPoint(point);
+  EXPECT_EQ("15,10", point.ToString());
+
   Shell::GetInstance()->RemovePreTargetHandler(&event_handler);
 }
 
 TEST_F(DisplayControllerTest, Rotate) {
   if (!SupportsMultipleDisplays())
     return;
 
   DisplayController* display_controller =
       Shell::GetInstance()->display_controller();
   internal::DisplayManager* display_manager =
@@ skipping 212 matching lines @@
   EXPECT_EQ("aura_root_x", GetXWindowName(secondary));
 
   // Switching back to single display.
   UpdateDisplay("300x400");
   EXPECT_EQ("aura_root_0", GetXWindowName(Shell::GetPrimaryRootWindow()));
 }
 #endif
 
 }  // namespace test
 }  // namespace ash