cc: Do GatherPixelRefs from skia at record time

cc/resources/picture.h

Index: cc/resources/picture.h
diff --git a/cc/resources/picture.h b/cc/resources/picture.h
index 8598fbf62b3c0a7ce983c9acd10737ef19e71d4a..e4a5a0015f54d202f170479ffba0f985f20e896b 100644
--- a/cc/resources/picture.h
+++ b/cc/resources/picture.h
@@ -6,11 +6,14 @@
 #define CC_RESOURCES_PICTURE_H_
 
 #include <list>
+#include <utility>
 #include <vector>
 
 #include "base/basictypes.h"
+#include "base/hash_tables.h"
 #include "base/memory/ref_counted.h"
 #include "cc/base/cc_export.h"
+#include "cc/base/hash_pair.h"
 #include "skia/ext/lazy_pixel_ref.h"
 #include "skia/ext/refptr.h"
 #include "third_party/skia/include/core/SkPixelRef.h"
@@ -60,14 +63,24 @@ class CC_EXPORT Picture
       std::list<skia::LazyPixelRef*>& pixel_ref_list);
 
  private:
+  typedef base::hash_map<
+      std::pair<int, int>,
+      std::list<skia::LazyPixelRef*> > PixelRefsMap;
+
   explicit Picture(gfx::Rect layer_rect);
   // This constructor assumes SkPicture is already ref'd and transfers
   // ownership to this picture.
   Picture(const skia::RefPtr<SkPicture>&,
           gfx::Rect layer_rect,
-          gfx::Rect opaque_rect);
+          gfx::Rect opaque_rect,
+          const PixelRefsMap& lazy_pixel_refs);
   ~Picture();
 
+  void GatherPixelRefsFromSkia(
+      const gfx::Rect& layer_rect,
+      std::list<skia::LazyPixelRef*>& pixel_ref_list);
+  void GatherAllPixelRefs();
+
   gfx::Rect layer_rect_;
   gfx::Rect opaque_rect_;
   skia::RefPtr<SkPicture> picture_;
@@ -75,6 +88,8 @@ class CC_EXPORT Picture
   typedef std::vector<scoped_refptr<Picture> > PictureVector;
   PictureVector clones_;
 
+  PixelRefsMap lazy_pixel_refs_;
+
   friend class base::RefCountedThreadSafe<Picture>;
   DISALLOW_COPY_AND_ASSIGN(Picture);
 };