Add UMA to check whether requestAudioFocus() is successful.

content/browser/media/android/media_session_uma_helper.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/browser/media/android/media_session_uma_helper.h"
 
 #include <utility>
 
 #include "base/metrics/histogram_base.h"
 #include "base/metrics/histogram_macros.h"
@@ skipping 11 matching lines @@
 {}
 
 void MediaSessionUmaHelper::RecordSessionSuspended(
     MediaSessionSuspendedSource source) const {
   UMA_HISTOGRAM_ENUMERATION(
       "Media.Session.Suspended",
       static_cast<HistogramBase::Sample>(source),
       static_cast<HistogramBase::Sample>(MediaSessionSuspendedSource::Count));
 }
 
+void MediaSessionUmaHelper::RecordRequestAudioFocusResult(bool result) const {
+  UMA_HISTOGRAM_BOOLEAN("Media.Session.RequestAudioFocusResult", result);
+}
+
 void MediaSessionUmaHelper::OnSessionActive() {
   current_active_time_ = clock_->Now();
 }
 
 void MediaSessionUmaHelper::OnSessionSuspended() {
   if (current_active_time_.is_null())
     return;
 
   total_active_time_ += clock_->Now() - current_active_time_;
   current_active_time_ = base::Time();
@@ skipping 11 matching lines @@
   UMA_HISTOGRAM_LONG_TIMES("Media.Session.ActiveTime", total_active_time_);
   total_active_time_ = base::TimeDelta();
 }
 
 void MediaSessionUmaHelper::SetClockForTest(
     scoped_ptr<base::Clock> testing_clock) {
   clock_ = std::move(testing_clock);
 }
 
 }  // namespace content