Introduce PlatformBitmap, which is a minimal helper class that wraps an SkBitmap

content/browser/renderer_host/render_widget_host_view_mac.mm

 // 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 "content/browser/renderer_host/render_widget_host_view_mac.h"
 
 #include <QuartzCore/QuartzCore.h>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 815 matching lines @@
 BackingStore* RenderWidgetHostViewMac::AllocBackingStore(
     const gfx::Size& size) {
   float scale = ScaleFactor(cocoa_view_);
   return new BackingStoreMac(render_widget_host_, size, scale);
 }
 
 void RenderWidgetHostViewMac::CopyFromCompositingSurface(
     const gfx::Rect& src_subrect,
     const gfx::Size& dst_size,
     const base::Callback<void(bool)>& callback,
-    skia::PlatformCanvas* output) {
+    skia::PlatformBitmap* output) {
   base::ScopedClosureRunner scoped_callback_runner(base::Bind(callback, false));
   if (!compositing_iosurface_.get() ||
       !compositing_iosurface_->HasIOSurface())
     return;
 
   float scale = ScaleFactor(cocoa_view_);
   gfx::Size dst_pixel_size = dst_size.Scale(scale);
-  if (!output->initialize(
+  if (!output->Allocate(
       dst_pixel_size.width(), dst_pixel_size.height(), true))
     return;
   scoped_callback_runner.Release();
 
   // Convert |src_subrect| from the views coordinate (upper-left origin) into
   // the OpenGL coordinate (lower-left origin).
   gfx::Rect src_gl_subrect = src_subrect;
   src_gl_subrect.set_y(GetViewBounds().height() - src_subrect.bottom());
 
   gfx::Rect src_pixel_gl_subrect =
       gfx::ToEnclosingRect(src_gl_subrect.Scale(scale));
   compositing_iosurface_->CopyTo(
       src_pixel_gl_subrect,
       dst_pixel_size,
-      output->getTopDevice()->accessBitmap(true).getPixels(),
+      output->GetBitmap().getPixels(),
       callback);
 }
 
 // Sets whether or not to accept first responder status.
 void RenderWidgetHostViewMac::SetTakesFocusOnlyOnMouseDown(bool flag) {
   [cocoa_view_ setTakesFocusOnlyOnMouseDown:flag];
 }
 
 void RenderWidgetHostViewMac::ForwardMouseEvent(const WebMouseEvent& event) {
   if (render_widget_host_)
@@ skipping 2429 matching lines @@
   if (!string) return NO;
 
   // If the user is currently using an IME, confirm the IME input,
   // and then insert the text from the service, the same as TextEdit and Safari.
   [self confirmComposition];
   [self insertText:string];
   return YES;
 }
 
 @end