Normalize top controls offset to (0, 1), Chromium-side.

cc/trees/layer_tree_impl.h

Index: cc/trees/layer_tree_impl.h
diff --git a/cc/trees/layer_tree_impl.h b/cc/trees/layer_tree_impl.h
index a58b645c501f023aa851751690abb91b358060ba..fef45743c2cf617a0afb7af9ae1855a66c506e6e 100644
--- a/cc/trees/layer_tree_impl.h
+++ b/cc/trees/layer_tree_impl.h
@@ -49,6 +49,7 @@ struct RendererCapabilities;
 struct SelectionHandle;
 
 typedef std::vector<UIResourceRequest> UIResourceRequestQueue;
+typedef SyncedProperty<AdditionGroup<float>> SyncedTopControls;
 typedef SyncedProperty<AdditionGroup<gfx::Vector2dF>> SyncedElasticOverscroll;
 
 class CC_EXPORT LayerTreeImpl {
@@ -56,9 +57,11 @@ class CC_EXPORT LayerTreeImpl {
   static scoped_ptr<LayerTreeImpl> create(
       LayerTreeHostImpl* layer_tree_host_impl,
       scoped_refptr<SyncedProperty<ScaleGroup>> page_scale_factor,
+      scoped_refptr<SyncedTopControls> top_controls_shown_ratio,
       scoped_refptr<SyncedElasticOverscroll> elastic_overscroll) {
-    return make_scoped_ptr(new LayerTreeImpl(
-        layer_tree_host_impl, page_scale_factor, elastic_overscroll));
+    return make_scoped_ptr(
+        new LayerTreeImpl(layer_tree_host_impl, page_scale_factor,
+                          top_controls_shown_ratio, elastic_overscroll));
   }
   virtual ~LayerTreeImpl();
 
@@ -185,6 +188,13 @@ class CC_EXPORT LayerTreeImpl {
     return elastic_overscroll_.get();
   }
 
+  SyncedTopControls* top_controls_shown_ratio() {
+    return top_controls_shown_ratio_.get();
+  }
+  const SyncedTopControls* top_controls_shown_ratio() const {
+    return top_controls_shown_ratio_.get();
+  }
+
   // Updates draw properties and render surface layer list, as well as tile
   // priorities. Returns false if it was unable to update.
   bool UpdateDrawProperties();
@@ -296,36 +306,17 @@ class CC_EXPORT LayerTreeImpl {
   void RegisterPictureLayerImpl(PictureLayerImpl* layer);
   void UnregisterPictureLayerImpl(PictureLayerImpl* layer);
 
-  void set_top_controls_shrink_blink_size(bool shrink) {
-    top_controls_shrink_blink_size_ = shrink;
-  }
-  void set_top_controls_height(float height) { top_controls_height_ = height; }
-  void set_top_controls_content_offset(float offset) {
-    top_controls_content_offset_ = offset;
-  }
-  void set_top_controls_delta(float delta) {
-    top_controls_delta_ = delta;
-  }
-  void set_sent_top_controls_delta(float sent_delta) {
-    sent_top_controls_delta_ = sent_delta;
-  }
-
+  void set_top_controls_shrink_blink_size(bool shrink);
   bool top_controls_shrink_blink_size() const {
     return top_controls_shrink_blink_size_;
   }
-  float top_controls_height() const { return top_controls_height_; }
-  float top_controls_content_offset() const {
-    return top_controls_content_offset_;
-  }
-  float top_controls_delta() const {
-    return top_controls_delta_;
-  }
-  float sent_top_controls_delta() const {
-    return sent_top_controls_delta_;
-  }
-  float total_top_controls_content_offset() const {
-    return top_controls_content_offset_ + top_controls_delta_;
+  bool SetCurrentTopControlsShownRatio(float ratio);
+  float CurrentTopControlsShownRatio() const {
+    return top_controls_shown_ratio_->Current(IsActiveTree());
   }
+  void set_top_controls_height(float top_controls_height);
+  float top_controls_height() const { return top_controls_height_; }
+  void PushTopControlsFromMainThread(float top_controls_shown_ratio);
 
   void SetPendingPageScaleAnimation(
       scoped_ptr<PendingPageScaleAnimation> pending_animation);
@@ -335,6 +326,7 @@ class CC_EXPORT LayerTreeImpl {
   explicit LayerTreeImpl(
       LayerTreeHostImpl* layer_tree_host_impl,
       scoped_refptr<SyncedProperty<ScaleGroup>> page_scale_factor,
+      scoped_refptr<SyncedTopControls> top_controls_shown_ratio,
       scoped_refptr<SyncedElasticOverscroll> elastic_overscroll);
   void ReleaseResourcesRecursive(LayerImpl* current);
   float ClampPageScaleFactorToLimits(float page_scale_factor) const;
@@ -345,7 +337,7 @@ class CC_EXPORT LayerTreeImpl {
                                 float max_page_scale_factor);
   void DidUpdatePageScale();
   void HideInnerViewportScrollbarsIfNearMinimumScale();
-
+  void PushTopControls(const float* top_controls_shown_ratio);
   LayerTreeHostImpl* layer_tree_host_impl_;
   int source_frame_number_;
   scoped_ptr<LayerImpl> root_layer_;
@@ -408,11 +400,9 @@ class CC_EXPORT LayerTreeImpl {
 
   float top_controls_height_;
 
-  // The up-to-date content offset of the top controls, i.e. the amount that the
-  // web contents have been shifted down from the top of the device viewport.
-  float top_controls_content_offset_;
-  float top_controls_delta_;
-  float sent_top_controls_delta_;
+  // The amount that the top controls are shown from 0 (hidden) to 1 (fully
+  // shown).
+  scoped_refptr<SyncedTopControls> top_controls_shown_ratio_;
 
   scoped_ptr<PendingPageScaleAnimation> pending_page_scale_animation_;