Intiialize AudioManager and related class lazily

content/browser/renderer_host/render_process_host_impl.cc

Index: content/browser/renderer_host/render_process_host_impl.cc
diff --git a/content/browser/renderer_host/render_process_host_impl.cc b/content/browser/renderer_host/render_process_host_impl.cc
index b1085f4db112e5a683f64a0fab25f6d6c1c1e54c..05d2a6bb0e65d159eefa3d3295549cfe43dbcf3b 100644
--- a/content/browser/renderer_host/render_process_host_impl.cc
+++ b/content/browser/renderer_host/render_process_host_impl.cc
@@ -188,6 +188,7 @@
 #include "content/browser/mojo/service_registrar_android.h"
 #include "content/browser/screen_orientation/screen_orientation_message_filter_android.h"
 #include "ipc/ipc_sync_channel.h"
+#include "media/audio/android/audio_manager_android.h"
 #endif
 
 #if defined(OS_WIN)
@@ -601,6 +602,17 @@ RenderProcessHostImpl::RenderProcessHostImpl(
   IPC::AttachmentBrokerPrivileged::CreateBrokerIfNeeded();
 #endif  // defined(OS_MACOSX)
 #endif  // USE_ATTACHMENT_BROKER
+
+#if !defined(OS_MACOSX)
+  // On Mac audio thread is the UI thread, a hang monitor is not
+  // necessary or recommended.
+  media::AudioManager::StartHangMonitor(

[no sievers, 2016/06/21 23:57:22]

Doesn't this blow up if being called repeatedly?

Maybe just needs a 'if (!BrowserMainLoop::GetInstance()->audio_manager())'?

[qinmin, 2016/06/22 00:15:56]

That doesn't work in ChromeOS case though since audio_manager() is already
created before renderer process are created.
I changed the AudioManagerHelper::StartHangTimer() to abort early if this is
already called.

+      BrowserThread::GetMessageLoopProxyForThread(BrowserThread::IO));
+#endif  // !defined(OS_MACOSX)
+#if defined(OS_ANDROID)
+  static_cast<media::AudioManagerAndroid*> (
+      media::AudioManager::Get())->InitializeIfNeeded();
+#endif  // defined(OS_ANDROID)
 }
 
 // static