telemetry: Refactored rasterize_and_record measurement.

cc/resources/picture.h

Index: cc/resources/picture.h
diff --git a/cc/resources/picture.h b/cc/resources/picture.h
index 6a7aca7e81722a5efaea14eb91903a9d73fa9a04..8210e86318b7dc0db01589d86121272888f6d8f5 100644
--- a/cc/resources/picture.h
+++ b/cc/resources/picture.h
@@ -68,10 +68,10 @@ class CC_EXPORT Picture
   bool HasRecording() const { return picture_.get() != NULL; }
 
   // Apply this contents scale and raster the content rect into the canvas.
-  void Raster(SkCanvas* canvas,
-              SkDrawPictureCallback* callback,
-              gfx::Rect content_rect,
-              float contents_scale);
+  int Raster(SkCanvas* canvas,
+             SkDrawPictureCallback* callback,
+             gfx::Rect content_rect,
+             float contents_scale);
 
   // Draw the picture directly into the given canvas, without applying any
   // clip/scale/layer transformations.