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

content/renderer/android/synchronous_compositor_filter.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 "content/renderer/android/synchronous_compositor_filter.h"
 
 #include <utility>
 
 #include "base/callback.h"
 #include "base/stl_util.h"
@@ skipping 223 matching lines @@
     const DidOverscrollParams& params) {
   DCHECK(compositor_task_runner_->BelongsToCurrentThread());
   SynchronousCompositorProxy* proxy = FindProxy(routing_id);
   if (!proxy) {
     DLOG(WARNING) << "No matching proxy in DidOverScroll " << routing_id;
     return;
   }
   proxy->DidOverscroll(params);
 }
 
+void SynchronousCompositorFilter::DidStartFlinging(int routing_id) {}
+
 void SynchronousCompositorFilter::DidStopFlinging(int routing_id) {
   DCHECK(compositor_task_runner_->BelongsToCurrentThread());
   Send(new InputHostMsg_DidStopFlinging(routing_id));
 }
 
 void SynchronousCompositorFilter::NotifyInputEventHandled(
     int routing_id,
     blink::WebInputEvent::Type type) {}
 
 void SynchronousCompositorFilter::DidAddSynchronousHandlerProxy(
@@ skipping 22 matching lines @@
 SynchronousCompositorFilter::Entry::Entry()
     : begin_frame_source(nullptr),
       output_surface(nullptr),
       synchronous_input_handler_proxy(nullptr) {}
 
 bool SynchronousCompositorFilter::Entry::IsReady() {
   return begin_frame_source && synchronous_input_handler_proxy;
 }
 
 }  // namespace content