Defer scroll status determination until scrolling has occurred

cc/trees/layer_tree_host_impl.h

 // Copyright 2011 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_HOST_IMPL_H_
 #define CC_TREES_LAYER_TREE_HOST_IMPL_H_
 
 #include <list>
 #include <set>
 #include <string>
@@ skipping 307 matching lines @@
 
   int scroll_layer_id_when_mouse_over_scrollbar() const {
     return scroll_layer_id_when_mouse_over_scrollbar_;
   }
   bool scroll_affects_scroll_handler() const {
     return scroll_affects_scroll_handler_;
   }
   void QueueSwapPromiseForMainThreadScrollUpdate(
       scoped_ptr<SwapPromise> swap_promise);
 
-  bool IsCurrentlyScrolling() const;
+  bool IsActivelyScrolling() const;
 
   virtual void SetVisible(bool visible);
   bool visible() const { return visible_; }
 
   void SetNeedsCommit() { client_->SetNeedsCommitOnImplThread(); }
   void SetNeedsRedraw();
 
   ManagedMemoryPolicy ActualManagedMemoryPolicy() const;
 
   size_t memory_allocation_limit_bytes() const;
@@ skipping 371 matching lines @@
   std::vector<PictureLayerImpl::Pair> picture_layer_pairs_;
 
   bool requires_high_res_to_draw_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHostImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_HOST_IMPL_H_