Reland: Force calling PostDisplayConfigurationChange() even if earyling out in UpdateDisplays

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/ash_switches.h"
 #include "ash/display/display_info.h"
 #include "ash/display/display_layout_store.h"
 #include "ash/display/display_manager.h"
@@ skipping 637 matching lines @@
   UpdateDisplay("400x500*2,300x300");
   EXPECT_EQ(1, observer.CountAndReset());
   EXPECT_EQ(0, observer.GetFocusChangedCountAndReset());
   EXPECT_EQ(0, observer.GetActivationChangedCountAndReset());
   ASSERT_EQ(2, Shell::GetScreen()->GetNumDisplays());
   EXPECT_EQ("0,0 200x250", GetPrimaryDisplay().bounds().ToString());
   EXPECT_EQ("0,250 300x300", GetSecondaryDisplay().bounds().ToString());
 
   // No change
   UpdateDisplay("400x500*2,300x300");
-  EXPECT_EQ(0, observer.CountAndReset());
+  // We still call into Pre/PostDisplayConfigurationChange().
+  EXPECT_EQ(1, observer.CountAndReset());
   EXPECT_EQ(0, observer.GetFocusChangedCountAndReset());
   EXPECT_EQ(0, observer.GetActivationChangedCountAndReset());
 
   // Rotation
   observer.GetRotationChangedCountAndReset();  // we only want to reset.
   int64 primary_id = GetPrimaryDisplay().id();
   display_manager->SetDisplayRotation(primary_id, gfx::Display::ROTATE_90);
   EXPECT_EQ(1, observer.GetRotationChangedCountAndReset());
   EXPECT_EQ(1, observer.CountAndReset());
   EXPECT_EQ(0, observer.GetFocusChangedCountAndReset());
@@ skipping 665 matching lines @@
   EXPECT_EQ("aura_root_x", GetXWindowName(secondary->GetHost()));
 
   // Switching back to single display.
   UpdateDisplay("300x400");
   EXPECT_EQ("aura_root_0", GetXWindowName(
       Shell::GetPrimaryRootWindow()->GetHost()));
 }
 #endif
 
 }  // namespace ash