Remove TransparentActivateWindowButton from Overview Mode

ash/wm/overview/scoped_overview_animation_settings.cc

 // Copyright 2014 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/wm/overview/scoped_overview_animation_settings.h"
 
 #include "ash/wm/overview/overview_animation_type.h"
 #include "base/time/time.h"
 #include "ui/aura/window.h"
 #include "ui/compositor/layer.h"
@@ skipping 55 matching lines @@
           ui::LayerAnimator::IMMEDIATELY_ANIMATE_TO_NEW_TARGET);
       break;
   }
   animation_settings_.SetTransitionDuration(
       GetAnimationDuration(animation_type));
 }
 
 ScopedOverviewAnimationSettings::~ScopedOverviewAnimationSettings() {
 }
 
+// static:
+void ScopedOverviewAnimationSettings::SetupFadeInAfterLayout(
+    aura::Window* window) {
+  ui::Layer* layer = window->layer();
+  layer->SetOpacity(0.0f);
+  ScopedOverviewAnimationSettings animation_settings(
+      OverviewAnimationType::OVERVIEW_ANIMATION_ENTER_OVERVIEW_MODE_FADE_IN,
+      window);
+  layer->SetOpacity(1.0f);
+}
+
 }  // namespace ash