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

content/browser/renderer_host/backing_store_win.cc

Index: content/browser/renderer_host/backing_store_win.cc
===================================================================
--- content/browser/renderer_host/backing_store_win.cc	(revision 161107)
+++ content/browser/renderer_host/backing_store_win.cc	(working copy)
@@ -159,12 +159,11 @@
 }
 
 bool BackingStoreWin::CopyFromBackingStore(const gfx::Rect& rect,
-                                           skia::PlatformCanvas* output) {
-  if (!output->initialize(rect.width(), rect.height(), true))
+                                           skia::PlatformBitmap* output) {
+  if (!output->Allocate(rect.width(), rect.height(), true))
     return false;
 
-  skia::ScopedPlatformPaint scoped_platform_paint(output);
-  HDC temp_dc = scoped_platform_paint.GetPlatformSurface();
+  HDC temp_dc = output->GetSurface();
   BitBlt(temp_dc, 0, 0, rect.width(), rect.height(),
          hdc(), rect.x(), rect.y(), SRCCOPY);
   return true;