[ash-md] Improves smoothness with many windows in overview

ash/frame/custom_frame_view_ash.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/frame/custom_frame_view_ash.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "ash/aura/wm_window_aura.h"
 #include "ash/common/ash_switches.h"
+#include "ash/common/material_design/material_design_controller.h"
 #include "ash/common/session/session_state_delegate.h"
 #include "ash/common/shell_observer.h"
 #include "ash/common/wm/window_state.h"
 #include "ash/common/wm/window_state_delegate.h"
 #include "ash/common/wm/window_state_observer.h"
 #include "ash/common/wm_lookup.h"
 #include "ash/common/wm_shell.h"
 #include "ash/frame/caption_buttons/frame_caption_button_container_view.h"
 #include "ash/frame/default_header_painter.h"
 #include "ash/frame/frame_border_hit_test_controller.h"
@@ skipping 136 matching lines @@
   void SizeConstraintsChanged();
 
   void SetFrameColors(SkColor active_frame_color, SkColor inactive_frame_color);
 
   // views::View:
   void Layout() override;
   void OnPaint(gfx::Canvas* canvas) override;
   void ChildPreferredSizeChanged(views::View* child) override;
 
   // ShellObserver:
+  void OnOverviewModeStarting() override;
+  void OnOverviewModeEnded() override;
   void OnMaximizeModeStarted() override;
   void OnMaximizeModeEnded() override;
 
   FrameCaptionButtonContainerView* caption_button_container() {
     return caption_button_container_;
   }
 
   views::View* avatar_icon() const { return avatar_icon_; }
 
  private:
@@ skipping 125 matching lines @@
   // until the completion of the animation. Layout in response to the preferred
   // size changes.
   if (child != caption_button_container_)
     return;
   parent()->Layout();
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 // CustomFrameViewAsh::HeaderView, ShellObserver overrides:
 
+void CustomFrameViewAsh::HeaderView::OnOverviewModeStarting() {
+  if (ash::MaterialDesignController::IsOverviewMaterial())
+    caption_button_container_->SetVisible(false);
+}
+
+void CustomFrameViewAsh::HeaderView::OnOverviewModeEnded() {
+  if (ash::MaterialDesignController::IsOverviewMaterial())
+    caption_button_container_->SetVisible(true);
+}
+
 void CustomFrameViewAsh::HeaderView::OnMaximizeModeStarted() {
   caption_button_container_->UpdateSizeButtonVisibility();
   parent()->Layout();
 }
 
 void CustomFrameViewAsh::HeaderView::OnMaximizeModeEnded() {
   caption_button_container_->UpdateSizeButtonVisibility();
   parent()->Layout();
 }
 
@@ skipping 266 matching lines @@
 FrameCaptionButtonContainerView*
 CustomFrameViewAsh::GetFrameCaptionButtonContainerViewForTest() {
   return header_view_->caption_button_container();
 }
 
 int CustomFrameViewAsh::NonClientTopBorderHeight() const {
   return frame_->IsFullscreen() ? 0 : header_view_->GetPreferredHeight();
 }
 
 }  // namespace ash