No need to kClear_Mode a layer right after its created, as that will automatically

chrome/browser/ui/views/tabs/tab.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 "chrome/browser/ui/views/tabs/tab.h"
 
 #include <limits>
 
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/defaults.h"
@@ skipping 572 matching lines @@
   } else {
     if (mini_title_animation_.get() && mini_title_animation_->is_animating())
       PaintInactiveTabBackgroundWithTitleChange(canvas);
     else
       PaintInactiveTabBackground(canvas);
 
     double throb_value = GetThrobValue();
     if (throb_value > 0) {
       canvas->SaveLayerAlpha(static_cast<int>(throb_value * 0xff),
                              gfx::Rect(width(), height()));
-      canvas->sk_canvas()->drawARGB(0, 255, 255, 255, SkXfermode::kClear_Mode);
       PaintActiveTabBackground(canvas, GetTabBackgroundImage(data().mode));
       canvas->Restore();
     }
   }
 }
 
 void Tab::PaintInactiveTabBackgroundWithTitleChange(gfx::Canvas* canvas) {
   // Render the inactive tab background. We'll use this for clipping.
   gfx::Canvas background_canvas(size(), canvas->scale_factor(), false);
   PaintInactiveTabBackground(&background_canvas);
@@ skipping 310 matching lines @@
                          const gfx::ImageSkia& image) {
   ImageCacheEntry entry;
   entry.resource_id = resource_id;
   entry.scale_factor = scale_factor;
   entry.image = image;
   entry.instant_images = instant_images;
   image_cache_->push_front(entry);
   if (image_cache_->size() > kMaxImageCacheSize)
     image_cache_->pop_back();
 }