Disable enumeration caching for output devices.

content/browser/renderer_host/media/audio_renderer_host.cc

 // Copyright (c) 2012 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/renderer_host/media/audio_renderer_host.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/logging.h"
 #include "base/memory/shared_memory.h"
@@ skipping 81 matching lines @@
     return false;
 
   for (const char& c : device_id) {
     if ((c < 'a' || c > 'f') && (c < '0' || c > '9'))
       return false;
   }
 
   return true;
 }
 
+bool IsDefaultDeviceId(const std::string& device_id) {
+  return device_id.empty() ||
+         device_id == media::AudioManagerBase::kDefaultDeviceId;
+}
+
+AudioOutputDeviceInfo GetDefaultDeviceInfoOnDeviceThread(
+    media::AudioManager* audio_manager) {
+  DCHECK(audio_manager->GetWorkerTaskRunner()->BelongsToCurrentThread());
+  AudioOutputDeviceInfo default_device_info = {
+      media::AudioManagerBase::kDefaultDeviceId,
+      audio_manager->GetDefaultDeviceName(),
+      audio_manager->GetDefaultOutputStreamParameters()};
+
+  return default_device_info;
+}
+
 void NotifyRenderProcessHostThatAudioStateChanged(int render_process_id) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   RenderProcessHost* render_process_host =
       RenderProcessHost::FromID(render_process_id);
 
   if (render_process_host)
     render_process_host->AudioStateChanged();
 }
 
@@ skipping 341 matching lines @@
     return;
 
   if (!have_access) {
     authorizations_.erase(auth_data);
     Send(new AudioMsg_NotifyDeviceAuthorized(
         stream_id, media::OUTPUT_DEVICE_STATUS_ERROR_NOT_AUTHORIZED,
         DummyParams()));
     return;
   }
 
-  media_stream_manager_->audio_output_device_enumerator()->Enumerate(base::Bind(
-      &AudioRendererHost::TranslateDeviceID, this, device_id,
-      gurl_security_origin,
-      base::Bind(&AudioRendererHost::OnDeviceIDTranslated, this, stream_id)));
+  // If enumerator caching is disabled, avoid the enumeration if the default
+  // device is requested, since no device ID translation is needed.
+  // If enumerator caching is enabled, it is better to use its cache, even
+  // for the default device.
+  if (IsDefaultDeviceId(device_id) &&
+      !media_stream_manager_->audio_output_device_enumerator()
+           ->IsCacheEnabled()) {
+    base::PostTaskAndReplyWithResult(
+        audio_manager_->GetWorkerTaskRunner().get(), FROM_HERE,
+        base::Bind(&GetDefaultDeviceInfoOnDeviceThread, audio_manager_),
+        base::Bind(&AudioRendererHost::OnDeviceIDTranslated, this, stream_id,
+                   true));
+  } else {
+    media_stream_manager_->audio_output_device_enumerator()->Enumerate(
+        base::Bind(&AudioRendererHost::TranslateDeviceID, this, device_id,
+                   gurl_security_origin,
+                   base::Bind(&AudioRendererHost::OnDeviceIDTranslated, this,
+                              stream_id)));
+  }
 }
 
 void AudioRendererHost::OnDeviceIDTranslated(
     int stream_id,
     bool device_found,
     const AudioOutputDeviceInfo& device_info) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   const auto& auth_data = authorizations_.find(stream_id);
 
   // A close request was received while translation was in progress
@@ skipping 314 matching lines @@
   callback.Run(false, device_info);
 }
 
 bool AudioRendererHost::IsAuthorizationStarted(int stream_id) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   const auto& i = authorizations_.find(stream_id);
   return i != authorizations_.end();
 }
 
 }  // namespace content