compositor-worker: cc->blink mutation plumbing

content/renderer/render_widget.cc

Index: content/renderer/render_widget.cc
diff --git a/content/renderer/render_widget.cc b/content/renderer/render_widget.cc
index 244d5ceb7533c4a69ca0fb75b9ee54c11e66b4ec..e7653a79b102f39f559f4061fc7c29ae51fd385a 100644
--- a/content/renderer/render_widget.cc
+++ b/content/renderer/render_widget.cc
@@ -1000,6 +1000,12 @@ void RenderWidget::ApplyViewportDeltas(
                                   top_controls_delta);
 }
 
+void RenderWidget::ApplyMutations(const cc::LayerTreeMutations& mutations) {
+  TRACE_EVENT0("compositor-worker", "RenderWidget::ApplyMutations");
+  webwidget_->applyMutations(
+      static_cast<const blink::WebCompositorMutations&>(mutations));
+}
+
 void RenderWidget::BeginMainFrame(double frame_time_sec) {
   webwidget_->beginFrame(frame_time_sec);
 }