Back PaintRecord with PaintOpBuffer instead of SkPicture

cc/paint/paint_canvas.h

Index: cc/paint/paint_canvas.h
diff --git a/cc/paint/paint_canvas.h b/cc/paint/paint_canvas.h
index 86348f075d1101b27e216eb89ec2b9597d09969e..e1fa9d0b7ad778a6a5dfb155178ea5aa1fd617b0 100644
--- a/cc/paint/paint_canvas.h
+++ b/cc/paint/paint_canvas.h
@@ -11,19 +11,25 @@
 #include "build/build_config.h"
 #include "cc/paint/paint_export.h"
 #include "cc/paint/paint_image.h"
-#include "cc/paint/paint_record.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 
 namespace cc {
 
 class DisplayItemList;
 class PaintFlags;
+class PaintOpBuffer;
+
+using PaintRecord = PaintOpBuffer;
 
 class CC_PAINT_EXPORT PaintCanvas {
  public:
+  PaintCanvas() {}
   virtual ~PaintCanvas() {}
 
   virtual SkMetaData& getMetaData() = 0;
+
+  // TODO(enne): this only appears to mostly be used to determine if this is
+  // recording or not, so could be simplified or removed.
   virtual SkImageInfo imageInfo() const = 0;
 
   // TODO(enne): It would be nice to get rid of flush() entirely, as it
@@ -36,7 +42,7 @@ class CC_PAINT_EXPORT PaintCanvas {
 
   virtual int save() = 0;
   virtual int saveLayer(const SkRect* bounds, const PaintFlags* flags) = 0;
-  virtual int saveLayerAlpha(const SkRect* bounds, U8CPU alpha) = 0;
+  virtual int saveLayerAlpha(const SkRect* bounds, uint8_t alpha) = 0;
 
   virtual void restore() = 0;
   virtual int getSaveCount() const = 0;
@@ -87,6 +93,8 @@ class CC_PAINT_EXPORT PaintCanvas {
   virtual bool getDeviceClipBounds(SkIRect* bounds) const = 0;
   virtual void drawColor(SkColor color, SkBlendMode mode) = 0;
   void drawColor(SkColor color) { drawColor(color, SkBlendMode::kSrcOver); }
+
+  // TODO(enne): This is a synonym for drawColor with kSrc.  Remove it.
   virtual void clear(SkColor color) = 0;
 
   virtual void drawLine(SkScalar x0,
@@ -180,6 +188,9 @@ class CC_PAINT_EXPORT PaintCanvas {
  protected:
   friend class PaintSurface;
   friend class PaintRecorder;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(PaintCanvas);
 };
 
 class CC_PAINT_EXPORT PaintCanvasAutoRestore {