Intiialize AudioManager and related class lazily

content/browser/browser_main_loop.cc

Index: content/browser/browser_main_loop.cc
diff --git a/content/browser/browser_main_loop.cc b/content/browser/browser_main_loop.cc
index b53236dd828b8a7eaeffe2e4de7ee55406f8a46b..26c082e3853899b3e08b2f2c4b0db36864135c58 100644
--- a/content/browser/browser_main_loop.cc
+++ b/content/browser/browser_main_loop.cc
@@ -1229,11 +1229,6 @@ int BrowserMainLoop::BrowserThreadsStarted() {
 #endif
 
   {
-    TRACE_EVENT0("startup", "BrowserThreadsStarted::Subsystem:AudioMan");
-    CreateAudioManager();
-  }
-
-  {
     TRACE_EVENT0("startup", "BrowserThreadsStarted::Subsystem:MidiManager");
     midi_manager_.reset(media::midi::MidiManager::Create());
   }
@@ -1258,20 +1253,6 @@ int BrowserMainLoop::BrowserThreadsStarted() {
     resource_dispatcher_host_.reset(new ResourceDispatcherHostImpl());
   }
 
-  // MediaStreamManager needs the IO thread to be created.
-  {
-    TRACE_EVENT0("startup",
-      "BrowserMainLoop::BrowserThreadsStarted:InitMediaStreamManager");
-    media_stream_manager_.reset(new MediaStreamManager(audio_manager_.get()));
-  }
-
-  {
-    TRACE_EVENT0("startup",
-      "BrowserMainLoop::BrowserThreadsStarted:InitSpeechRecognition");
-    speech_recognition_manager_.reset(new SpeechRecognitionManagerImpl(
-        audio_manager_.get(), media_stream_manager_.get()));
-  }
-
   {
     TRACE_EVENT0(
         "startup",
@@ -1466,9 +1447,11 @@ void BrowserMainLoop::EndStartupTracing() {
           base::Bind(OnStoppedStartupTracing, startup_trace_file_)));
 }
 
-void BrowserMainLoop::CreateAudioManager() {
+media::AudioManager* BrowserMainLoop::GetAudioManager() {

[tommi (sloooow) - chröme, 2016/06/18 13:49:03]

make sure this always runs on the same thread

[qinmin, 2016/06/20 23:45:29]

Done.

+  if (audio_manager_)
+    return audio_manager_.get();
+
   DCHECK(!audio_thread_);
-  DCHECK(!audio_manager_);
 
   bool use_hang_monitor = true;
   audio_manager_ = GetContentClient()->browser()->CreateAudioManager(
@@ -1501,6 +1484,25 @@ void BrowserMainLoop::CreateAudioManager() {
 
   if (use_hang_monitor)
     media::AudioManager::StartHangMonitor(io_thread_->task_runner());
+  return audio_manager_.get();
+}
+
+MediaStreamManager* BrowserMainLoop::GetMediaStreamManager() {
+  if (media_stream_manager_)
+    return media_stream_manager_.get();
+
+  GetAudioManager();
+  media_stream_manager_.reset(new MediaStreamManager(audio_manager_.get()));

[no sievers, 2016/06/18 00:17:20]

nit: or just write newMediaStreamManager(GetAudioManager());

[qinmin, 2016/06/20 23:45:29]

no longer needed with the new patch

+  return media_stream_manager_.get();
+}
+
+void BrowserMainLoop::InitializeSpeechRecognitionManager() {
+  if (speech_recognition_manager_)
+    return;
+
+  GetMediaStreamManager();
+  speech_recognition_manager_.reset(new SpeechRecognitionManagerImpl(
+         audio_manager_.get(), media_stream_manager_.get()));

[no sievers, 2016/06/18 00:17:20]

nit: same here

[qinmin, 2016/06/20 23:45:29]

no longer needed with the new patch

 }
 
 }  // namespace content