Disable enumeration caching for output devices.

content/browser/renderer_host/media/audio_output_device_enumerator.h

 // Copyright (c) 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.
 
 // AudioOutputDeviceEnumerator is used to enumerate audio output devices.
 // It can return cached results of previous enumerations in order to boost
 // performance.
 // All its public methods must be called on the thread where the object is
 // created.
 
@@ skipping 54 matching lines @@
   // provides default parameters, even if there are no devices.
   // See https://crbug.com/549125.
   void Enumerate(const AudioOutputDeviceEnumerationCB& callback);
 
   // Invalidates the current cache.
   void InvalidateCache();
 
   // Sets the cache policy.
   void SetCachePolicy(CachePolicy cache_policy);
 
+  // Returns true if the caching policy is different from
+  // CACHE_POLICY_NO_CACHING, false otherwise.
+  bool IsCacheEnabled();
+
  private:
   void InitializeOnIOThread();
   void DoEnumerateDevices();
   AudioOutputDeviceEnumeration DoEnumerateDevicesOnDeviceThread();
   void DevicesEnumerated(const AudioOutputDeviceEnumeration& snapshot);
   int64_t NewEventSequence();
   bool IsLastEnumerationValid() const;
 
   media::AudioManager* const audio_manager_;
   CachePolicy cache_policy_;
   AudioOutputDeviceEnumeration cache_;
   std::list<AudioOutputDeviceEnumerationCB> pending_callbacks_;
 
   // sequential number that serves as logical clock
   int64_t current_event_sequence_;
 
   int64_t seq_last_enumeration_;
   int64_t seq_last_invalidation_;
   bool is_enumeration_ongoing_;
 
   base::ThreadChecker thread_checker_;
   base::WeakPtrFactory<AudioOutputDeviceEnumerator> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioOutputDeviceEnumerator);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_AUDIO_OUTPUT_DEVICE_ENUMERATOR_H_