cc/blimp: Add synchronization for scroll/scale state.

cc/trees/layer_tree.cc

Index: cc/trees/layer_tree.cc
diff --git a/cc/trees/layer_tree.cc b/cc/trees/layer_tree.cc
index 3d46e3fae10b4ccb39fac6c7b0116a0f9f1cd40c..75b5aec157716a7f8e95d529f6ff45f7ae3aa4e0 100644
--- a/cc/trees/layer_tree.cc
+++ b/cc/trees/layer_tree.cc
@@ -423,6 +423,11 @@ void LayerTree::PushPropertiesTo(LayerTreeImpl* tree_impl) {
         std::move(inputs_.pending_page_scale_animation));
   }
 
+  if (inputs_.reflected_main_frame_state) {
+    tree_impl->SetReflectedMainFrameState(
+        std::move(inputs_.reflected_main_frame_state));
+  }
+
   DCHECK(!tree_impl->ViewportSizeInvalid());
 
   tree_impl->set_has_ever_been_drawn(false);
@@ -697,4 +702,10 @@ void LayerTree::SetNeedsDisplayOnAllLayers() {
     layer->SetNeedsDisplay();
 }
 
+void LayerTree::SetReflectedMainFrameState(
+    std::unique_ptr<ReflectedMainFrameState> reflected_main_frame_state) {
+  inputs_.reflected_main_frame_state = std::move(reflected_main_frame_state);
+  SetNeedsCommit();
+}
+
 }  // namespace cc