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

chrome/browser/prerender/prerender_tab_helper.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/prerender/prerender_tab_helper.h"
 
 #include "base/metrics/histogram.h"
 #include "base/string_number_conversions.h"
 #include "base/time.h"
 #include "chrome/browser/prerender/prerender_histograms.h"
@@ skipping 37 matching lines @@
     }
 
     if (bitmap_type == BITMAP_ON_LOAD && bitmap_web_contents_ != web_contents)
       return;
 
     if (!web_contents || !web_contents->GetView() ||
         !web_contents->GetRenderViewHost()) {
       return;
     }
 
-    skia::PlatformCanvas* temp_canvas = new skia::PlatformCanvas;
+    skia::PlatformBitmap* temp_bitmap = new skia::PlatformBitmap;
     web_contents->GetRenderViewHost()->CopyFromBackingStore(
         gfx::Rect(),
         gfx::Size(),
         base::Bind(&PrerenderTabHelper::PixelStats::HandleBitmapResult,
                    weak_factory_.GetWeakPtr(),
                    bitmap_type,
                    web_contents,
-                   base::Owned(temp_canvas)),
-        temp_canvas);
+                   base::Owned(temp_bitmap)),
+        temp_bitmap);
   }
 
  private:
   void HandleBitmapResult(BitmapType bitmap_type,
                           WebContents* web_contents,
-                          skia::PlatformCanvas* temp_canvas,
+                          skia::PlatformBitmap* temp_bitmap,
                           bool succeeded) {
     scoped_ptr<SkBitmap> bitmap;
     if (succeeded) {
-      const SkBitmap& canvas_bitmap =
-          skia::GetTopDevice(*temp_canvas)->accessBitmap(false);
+        const SkBitmap& canvas_bitmap = temp_bitmap->GetBitmap();
       bitmap.reset(new SkBitmap());
       canvas_bitmap.copyTo(bitmap.get(), SkBitmap::kARGB_8888_Config);
     }
 
     if (bitmap_web_contents_ != web_contents)
       return;
 
     if (bitmap_type == BITMAP_SWAP_IN)
       bitmap_.swap(bitmap);
 
@@ skipping 156 matching lines @@
     // If we have not finished loading yet, record the actual load start, and
     // rebase the start time to now.
     actual_load_start_ = pplt_load_start_;
     pplt_load_start_ = base::TimeTicks::Now();
     if (pixel_stats_.get())
       pixel_stats_->GetBitmap(PixelStats::BITMAP_SWAP_IN, web_contents());
   }
 }
 
 }  // namespace prerender