[cc] Cleanup: modify the description of SkPictureContentLayerUpdater

cc/resources/skpicture_content_layer_updater.h

Index: cc/resources/skpicture_content_layer_updater.h
diff --git a/cc/resources/skpicture_content_layer_updater.h b/cc/resources/skpicture_content_layer_updater.h
index 511d8ee9bfd48b93254a9a22741a0b61859345b4..640dd5d86dd7e47aea0bea3f96d6acdd198dd368 100644
--- a/cc/resources/skpicture_content_layer_updater.h
+++ b/cc/resources/skpicture_content_layer_updater.h
@@ -14,11 +14,8 @@ namespace cc {
 
 class LayerPainter;
 
-// This class records the content_rect into an SkPicture. Subclasses, provide
-// different implementations of tile updating based on this recorded picture.
-// The BitmapSkPictureContentLayerUpdater and
-// FrameBufferSkPictureContentLayerUpdater are two examples of such
-// implementations.
+// This class records the content_rect into an SkPicture. Subclass provides
+// SkCanvas to DrawPicture() for tile updating based on this recorded picture.
 class SkPictureContentLayerUpdater : public ContentLayerUpdater {
  protected:
   SkPictureContentLayerUpdater(