compositor-worker: cc->blink mutation plumbing

content/test/web_layer_tree_view_impl_for_testing.h

Index: content/test/web_layer_tree_view_impl_for_testing.h
diff --git a/content/test/web_layer_tree_view_impl_for_testing.h b/content/test/web_layer_tree_view_impl_for_testing.h
index 4596be861bfc9dc8052a12c1edde86f6636d0cae..8e323048de1198a780e708b07962d513ebe2bce3 100644
--- a/content/test/web_layer_tree_view_impl_for_testing.h
+++ b/content/test/web_layer_tree_view_impl_for_testing.h
@@ -79,6 +79,7 @@ class WebLayerTreeViewImplForTesting
                            const gfx::Vector2dF& elastic_overscroll_delta,
                            float page_scale,
                            float top_controls_delta) override;
+  void ApplyMutations(const cc::LayerTreeMutations& mutations) override {}
   void RequestNewOutputSurface() override;
   void DidInitializeOutputSurface() override {}
   void DidFailToInitializeOutputSurface() override;