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

cc/trees/layer_tree.h

Index: cc/trees/layer_tree.h
diff --git a/cc/trees/layer_tree.h b/cc/trees/layer_tree.h
index 9f749bfe0770d6c3537f1d87033cce08f44f00df..afd645853d04fb4d4578e63d77ef7cca65be2a3b 100644
--- a/cc/trees/layer_tree.h
+++ b/cc/trees/layer_tree.h
@@ -42,6 +42,7 @@ class LayerTreeHost;
 class LayerTreeImpl;
 class LayerTreeSettings;
 struct PendingPageScaleAnimation;
+struct ReflectedMainFrameState;
 class UIResourceManager;
 class SwapPromiseManager;
 class SurfaceSequenceGenerator;
@@ -102,6 +103,8 @@ class CC_EXPORT LayerTree : public MutatorHostClient {
                                    float min_page_scale_factor,
                                    float max_page_scale_factor);
   float page_scale_factor() const { return inputs_.page_scale_factor; }
+  float min_page_scale_factor() const { return inputs_.min_page_scale_factor; }
+  float max_page_scale_factor() const { return inputs_.max_page_scale_factor; }
 
   void set_background_color(SkColor color) { inputs_.background_color = color; }
   SkColor background_color() const { return inputs_.background_color; }
@@ -132,6 +135,9 @@ class CC_EXPORT LayerTree : public MutatorHostClient {
 
   void SetNeedsDisplayOnAllLayers();
 
+  void SetReflectedMainFrameState(
+      std::unique_ptr<ReflectedMainFrameState> reflected_main_frame_state);
+
   void SetNeedsCommit();
 
   const LayerTreeSettings& GetSettings() const;
@@ -274,6 +280,8 @@ class CC_EXPORT LayerTree : public MutatorHostClient {
         EventListenerClass::kNumClasses)];
 
     std::unique_ptr<PendingPageScaleAnimation> pending_page_scale_animation;
+
+    std::unique_ptr<ReflectedMainFrameState> reflected_main_frame_state;
   };
 
   Inputs inputs_;