cc: Remove the opaque rect return-parameter from ContentLayerClient.

cc/resources/content_layer_updater.h

Index: cc/resources/content_layer_updater.h
diff --git a/cc/resources/content_layer_updater.h b/cc/resources/content_layer_updater.h
index 7dfcb6a794fc4360403fb0fa65e53ce8338a1c2a..c02759607c687f9869a7559e43fe14af03e27988 100644
--- a/cc/resources/content_layer_updater.h
+++ b/cc/resources/content_layer_updater.h
@@ -34,8 +34,7 @@ class CC_EXPORT ContentLayerUpdater : public LayerUpdater {
   void PaintContents(SkCanvas* canvas,
                      const gfx::Rect& content_rect,
                      float contents_width_scale,
-                     float contents_height_scale,
-                     gfx::Rect* resulting_opaque_rect);
+                     float contents_height_scale);
   gfx::Rect content_rect() const { return content_rect_; }
 
   bool layer_is_opaque() const { return layer_is_opaque_; }