Made Blink aware of top controls offset (Chromium-side)

cc/trees/layer_tree_impl.h

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_TREES_LAYER_TREE_IMPL_H_
 #define CC_TREES_LAYER_TREE_IMPL_H_
 
 #include <list>
 #include <string>
 #include <vector>
@@ skipping 273 matching lines @@
                          const LayerSelectionBound& end);
 
   // Compute the current selection handle location and visbility with respect to
   // the viewport.
   void GetViewportSelection(ViewportSelectionBound* start,
                             ViewportSelectionBound* end);
 
   void RegisterPictureLayerImpl(PictureLayerImpl* layer);
   void UnregisterPictureLayerImpl(PictureLayerImpl* layer);
 
+  void set_top_controls_layout_height(float height) {
+    top_controls_layout_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;
+  }
+
+  float top_controls_layout_height() const {
+    return top_controls_layout_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_;
+  }
+
  protected:
   explicit LayerTreeImpl(LayerTreeHostImpl* layer_tree_host_impl);
   void ReleaseResourcesRecursive(LayerImpl* current);
 
   LayerTreeHostImpl* layer_tree_host_impl_;
   int source_frame_number_;
   scoped_ptr<LayerImpl> root_layer_;
   HeadsUpDisplayLayerImpl* hud_layer_;
   LayerImpl* currently_scrolling_layer_;
   LayerScrollOffsetDelegate* root_layer_scroll_offset_delegate_;
@@ skipping 40 matching lines @@
   bool next_activation_forces_redraw_;
 
   bool has_ever_been_drawn_;
 
   ScopedPtrVector<SwapPromise> swap_promise_list_;
 
   UIResourceRequestQueue ui_resource_request_queue_;
 
   int render_surface_layer_list_id_;
 
+  // The top controls content offset at the time of the last layout (and thus,
+  // viewport resize) in Blink. i.e. How much the viewport was shrunk by the top
+  // controls.
+  float top_controls_layout_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_;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(LayerTreeImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_IMPL_H_