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

blimp/client/feature/compositor/blimp_input_handler_wrapper.cc

 // Copyright 2015 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.
 
 #include "blimp/client/feature/compositor/blimp_input_handler_wrapper.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "blimp/client/feature/compositor/blimp_input_manager.h"
@@ skipping 79 matching lines @@
 }
 
 void BlimpInputHandlerWrapper::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) {
   DCHECK(compositor_thread_checker_.CalledOnValidThread());
 }
 
+void BlimpInputHandlerWrapper::DidStartFlinging() {
+  DCHECK(compositor_thread_checker_.CalledOnValidThread());
+}
+
 void BlimpInputHandlerWrapper::DidStopFlinging() {
   DCHECK(compositor_thread_checker_.CalledOnValidThread());
 }
 
 void BlimpInputHandlerWrapper::DidAnimateForInput() {
   DCHECK(compositor_thread_checker_.CalledOnValidThread());
 }
 
 }  // namespace client
 }  // namespace blimp