[MediaRouter] Record DIAL device counts in DialMediaSinkServiceImpl

chrome/browser/media/router/media_router_metrics.h

 // 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.
 
 #ifndef CHROME_BROWSER_MEDIA_ROUTER_MEDIA_ROUTER_METRICS_H_
 #define CHROME_BROWSER_MEDIA_ROUTER_MEDIA_ROUTER_METRICS_H_
 
 #include "base/gtest_prod_util.h"
 #include "base/time/time.h"
 
@@ skipping 37 matching lines @@
   STATUS_REMOTE = 4,
   REPLACE_LOCAL_ROUTE = 5,
 
   // Note: Add entries only immediately above this line.
   TOTAL_COUNT = 6
 };
 
 class MediaRouterMetrics {
  public:
   // UMA histogram names.
+  static const char kDialAvailableDeviceCount[];
+  static const char kDialKnownDeviceCount[];
   static const char kHistogramIconClickLocation[];
   static const char kHistogramUiDialogPaint[];
   static const char kHistogramUiDialogLoadedWithData[];
   static const char kHistogramUiFirstAction[];
   static const char kHistogramRouteCreationOutcome[];
 
   // Records where the user clicked to open the Media Router dialog.
   static void RecordMediaRouterDialogOrigin(
       MediaRouterDialogOpenOrigin origin);
 
   // Records the duration it takes for the Media Router dialog to open and
   // finish painting after a user clicks to open the dialog.
   static void RecordMediaRouterDialogPaint(
       const base::TimeDelta delta);
 
   // Records the duration it takes for the Media Router dialog to load its
   // initial data after a user clicks to open the dialog.
   static void RecordMediaRouterDialogLoaded(
       const base::TimeDelta delta);
 
   // Records the first action the user took after the Media Router dialog
   // opened.
   static void RecordMediaRouterInitialUserAction(
       MediaRouterUserAction action);
 
   // Records the outcome in a create route response.
   static void RecordRouteCreationOutcome(
       MediaRouterRouteCreationOutcome outcome);
+
+  // Records device counts.
+  static void RecordDialDeviceCounts(size_t available_device_count,
+                                     size_t known_device_count);
 };
 
 }  // namespace media_router
 
 #endif  // CHROME_BROWSER_MEDIA_ROUTER_MEDIA_ROUTER_METRICS_H_