Remove RenderWidget::SetBackground, change IPC to pass a bool.

apps/ui/views/native_app_window_views.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 "apps/ui/views/native_app_window_views.h"
 
 #include "apps/app_window.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "content/public/browser/render_view_host.h"
 #include "content/public/browser/render_widget_host_view.h"
@@ skipping 244 matching lines @@
   app_window_->OnNativeWindowChanged();
   if (active)
     app_window_->OnNativeWindowActivated();
 }
 
 // WebContentsObserver implementation.
 
 void NativeAppWindowViews::RenderViewCreated(
     content::RenderViewHost* render_view_host) {
   if (transparent_background_) {
-    // Use a background with transparency to trigger transparency in Webkit.
-    SkBitmap background;
-    background.setConfig(SkBitmap::kARGB_8888_Config, 1, 1);
-    background.allocPixels();
-    background.eraseARGB(0x00, 0x00, 0x00, 0x00);
-
     content::RenderWidgetHostView* view = render_view_host->GetView();
     DCHECK(view);
-    view->SetBackground(background);
+    view->SetBackgroundOpaque(false);
   }
 }
 
 void NativeAppWindowViews::RenderViewHostChanged(
     content::RenderViewHost* old_host,
     content::RenderViewHost* new_host) {
   OnViewWasResized();
 }
 
 // views::View implementation.
@@ skipping 115 matching lines @@
   return size_constraints_.GetMaximumSize();
 }
 
 void NativeAppWindowViews::SetContentSizeConstraints(
     const gfx::Size& min_size, const gfx::Size& max_size) {
   size_constraints_.set_minimum_size(min_size);
   size_constraints_.set_maximum_size(max_size);
 }
 
 }  // namespace apps