compositor-worker: cc->blink mutation plumbing

cc/test/fake_layer_tree_host_client.h

Index: cc/test/fake_layer_tree_host_client.h
diff --git a/cc/test/fake_layer_tree_host_client.h b/cc/test/fake_layer_tree_host_client.h
index 7e2ba030186275205c970a6e49bd8653ed6318c8..7f17d709f282b868d2cffb13082d584f1f2b8351 100644
--- a/cc/test/fake_layer_tree_host_client.h
+++ b/cc/test/fake_layer_tree_host_client.h
@@ -40,6 +40,8 @@ class FakeLayerTreeHostClient : public LayerTreeHostClient,
                            const gfx::Vector2dF& elastic_overscroll_delta,
                            float page_scale,
                            float top_controls_delta) override {}
+  void ApplyMutations(const LayerTreeMutations& mutations) override {}
+
   void RequestNewOutputSurface() override;
   void DidInitializeOutputSurface() override {}
   void DidFailToInitializeOutputSurface() override;