cc: Fix low-res impl-side painting artifacts

cc/picture.h

Index: cc/picture.h
diff --git a/cc/picture.h b/cc/picture.h
index 361578cf56711a28b4693769a71592cc2fa90aa3..4672c367cc5f3163e3f14e1fb8f85cdd567c6744 100644
--- a/cc/picture.h
+++ b/cc/picture.h
@@ -39,9 +39,8 @@ public:
   // Has Record() been called yet?
   bool HasRecording() const { return picture_.get(); }
 
-  // Raster this Picture's layer_rect into the given canvas.
-  // Assumes contentsScale have already been applied.
-  void Raster(SkCanvas* canvas);
+  // Apply this contents scale and raster the content rect into the canvas.
+  void Raster(SkCanvas* canvas, gfx::Rect content_rect, float contents_scale);
 
   void GatherPixelRefs(const gfx::Rect& rect,
                        std::list<skia::LazyPixelRef*>&);