Make touch events uncancelable during fling when they are on the current active scroll layer

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 <stddef.h>
 
 #include <bitset>
@@ skipping 179 matching lines @@
                                bool anchor_point,
                                float page_scale,
                                base::TimeDelta duration);
   void SetNeedsAnimateInput() override;
   bool IsCurrentlyScrollingViewport() const override;
   bool IsCurrentlyScrollingLayerAt(
       const gfx::Point& viewport_point,
       InputHandler::ScrollInputType type) const override;
   EventListenerProperties GetEventListenerProperties(
       EventListenerClass event_class) const override;
-  bool DoTouchEventsBlockScrollAt(const gfx::Point& viewport_port) override;
+  InputHandler::TouchStartHitResult DoTouchEventsBlockScrollAt(
+      const gfx::Point& viewport_port) override;
   std::unique_ptr<SwapPromiseMonitor> CreateLatencyInfoSwapPromiseMonitor(
       ui::LatencyInfo* latency) override;
   ScrollElasticityHelper* CreateScrollElasticityHelper() override;
   bool GetScrollOffsetForLayer(int layer_id,
                                gfx::ScrollOffset* offset) override;
   bool ScrollLayerTo(int layer_id, const gfx::ScrollOffset& offset) override;
 
   // BrowserControlsOffsetManagerClient implementation.
   float TopControlsHeight() const override;
   float BottomControlsHeight() const override;
@@ skipping 624 matching lines @@
 
   std::unique_ptr<PendingTreeDurationHistogramTimer>
       pending_tree_duration_timer_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHostImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_HOST_IMPL_H_