cros: Fix immersive fullscreen tabstrip revealing does not draw well

ash/common/frame/header_view.cc

 // Copyright 2016 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/common/frame/header_view.h"
 
 #include "ash/common/frame/caption_buttons/frame_caption_button_container_view.h"
 #include "ash/common/frame/default_header_painter.h"
 #include "ash/common/session/session_state_delegate.h"
 #include "ash/common/wm_lookup.h"
@@ skipping 147 matching lines @@
   return avatar_icon_;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 // HeaderView,
 //   ImmersiveFullscreenControllerDelegate overrides:
 
 void HeaderView::OnImmersiveRevealStarted() {
   fullscreen_visible_fraction_ = 0;
   SetPaintToLayer();
+  layer()->SetFillsBoundsOpaquely(false);
   parent()->Layout();
 }
 
 void HeaderView::OnImmersiveRevealEnded() {
   fullscreen_visible_fraction_ = 0;
   DestroyLayer();
   parent()->Layout();
 }
 
 void HeaderView::OnImmersiveFullscreenExited() {
@@ skipping 14 matching lines @@
   gfx::Rect visible_bounds(GetVisibleBounds());
   gfx::Point visible_origin_in_screen(visible_bounds.origin());
   views::View::ConvertPointToScreen(this, &visible_origin_in_screen);
   std::vector<gfx::Rect> bounds_in_screen;
   bounds_in_screen.push_back(
       gfx::Rect(visible_origin_in_screen, visible_bounds.size()));
   return bounds_in_screen;
 }
 
 }  // namespace ash