[MediaRouter] Record DIAL device counts in DialMediaSinkServiceImpl

chrome/browser/media/router/discovery/dial/dial_media_sink_service_impl.cc

 // Copyright 2017 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 "chrome/browser/media/router/discovery/dial/dial_media_sink_service_impl.h"
 
 #include "chrome/browser/media/router/discovery/dial/dial_device_data.h"
 #include "chrome/browser/profiles/profile.h"
 #include "content/public/browser/browser_thread.h"
 #include "net/url_request/url_request_context_getter.h"
@@ skipping 111 matching lines @@
   MediaSinkServiceBase::RestartTimer();
 }
 
 void DialMediaSinkServiceImpl::OnDeviceDescriptionError(
     const DialDeviceData& device,
     const std::string& error_message) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   DVLOG(2) << "OnDescriptionFetchesError [message]: " << error_message;
 }
 
+void DialMediaSinkServiceImpl::RecordDeviceCounts() {
+  metrics_.RecordDialDeviceCounts(current_sinks_.size(),
+                                  current_devices_.size());
+}
+
 }  // namespace media_router