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

content/renderer/mus/compositor_mus_connection_unittest.cc

 // Copyright 2016 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/mus/compositor_mus_connection.h"
 
 #include <memory>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
@@ skipping 109 matching lines @@
  public:
   TestInputHandlerManagerClient() {}
   ~TestInputHandlerManagerClient() override{};
 
   // content::InputHandlerManagerClient:
   void SetBoundHandler(const Handler& handler) override {}
   void DidAddInputHandler(int routing_id) override {}
   void DidRemoveInputHandler(int routing_id) override {}
   void DidOverscroll(int routing_id,
                      const content::DidOverscrollParams& params) override {}
+  void DidStartFlinging(int routing_id) override {}
   void DidStopFlinging(int routing_id) override {}
   void NotifyInputEventHandled(int routing_id,
                                blink::WebInputEvent::Type type) override {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(TestInputHandlerManagerClient);
 };
 
 // Implementation of RenderWidget for testing, performs no initialization.
 class TestRenderWidget : public content::RenderWidget {
@@ skipping 338 matching lines @@
   EXPECT_FALSE(ack_callback.get());
 
   VerifyAndRunQueues(true, true);
 
   // The ack callback should have been called
   EXPECT_TRUE(test_callback->called());
   EXPECT_EQ(EventResult::HANDLED, test_callback->result());
 }
 
 }  // namespace content