Add UMA metric for tracking listeners for blocking touch while fling is happening

blimp/client/feature/compositor/blimp_input_handler_wrapper.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 BLIMP_CLIENT_FEATURE_COMPOSITOR_BLIMP_INPUT_HANDLER_WRAPPER_H_
 #define BLIMP_CLIENT_FEATURE_COMPOSITOR_BLIMP_INPUT_HANDLER_WRAPPER_H_
 
 #include "base/macros.h"
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread_checker.h"
@@ skipping 29 matching lines @@
   void TransferActiveWheelFlingAnimation(
       const blink::WebActiveWheelFlingParameters& params) override;
   blink::WebGestureCurve* CreateFlingAnimationCurve(
       blink::WebGestureDevice device_source,
       const blink::WebFloatPoint& velocity,
       const blink::WebSize& cumulative_scroll) override;
   void DidOverscroll(const gfx::Vector2dF& accumulated_overscroll,
                      const gfx::Vector2dF& latest_overscroll_delta,
                      const gfx::Vector2dF& current_fling_velocity,
                      const gfx::PointF& causal_event_viewport_point) override;
+  void DidStartFlinging() override;
   void DidStopFlinging() override;
   void DidAnimateForInput() override;
 
   base::ThreadChecker compositor_thread_checker_;
 
   scoped_refptr<base::SingleThreadTaskRunner> main_task_runner_;
 
   // Used to queue calls to the BlimpInputManager to be run on the main
   // thread. This ensures that any tasks queued are abandoned after the
   // BlimpInputManager is destroyed.
   base::WeakPtr<BlimpInputManager> input_manager_weak_ptr_;
 
   std::unique_ptr<ui::InputHandlerProxy> input_handler_proxy_;
 
   DISALLOW_COPY_AND_ASSIGN(BlimpInputHandlerWrapper);
 };
 
 }  // namespace client
 }  // namespace blimp
 
 #endif  // BLIMP_CLIENT_FEATURE_COMPOSITOR_BLIMP_INPUT_HANDLER_WRAPPER_H_