Revert of Pass task runners to AudioManager constructor.

content/browser/browser_main_loop.h

Index: content/browser/browser_main_loop.h
diff --git a/content/browser/browser_main_loop.h b/content/browser/browser_main_loop.h
index 4d3444586bc9b1859f4943b15ebbe3c9c2dd0848..70522111c06aa36ae49a42229c4b8b0ea1101b68 100644
--- a/content/browser/browser_main_loop.h
+++ b/content/browser/browser_main_loop.h
@@ -14,7 +14,6 @@
 #include "build/build_config.h"
 #include "content/browser/browser_process_sub_thread.h"
 #include "content/public/browser/browser_main_runner.h"
-#include "media/audio/audio_manager.h"
 
 #if defined(USE_AURA)
 namespace aura {
@@ -40,6 +39,7 @@
 }
 
 namespace media {
+class AudioManager;
 #if defined(OS_WIN)
 class SystemMessageWindowWin;
 #elif defined(OS_LINUX) && defined(USE_UDEV)
@@ -169,7 +169,6 @@
   void InitStartupTracingForDuration(const base::CommandLine& command_line);
   void EndStartupTracing();
 
-  void CreateAudioManager();
   bool UsingInProcessGpu() const;
 
   // Quick reference for initialization order:
@@ -261,9 +260,7 @@
 
   // |user_input_monitor_| has to outlive |audio_manager_|, so declared first.
   std::unique_ptr<media::UserInputMonitor> user_input_monitor_;
-  // AudioThread needs to outlive |audio_manager_|.
-  std::unique_ptr<base::Thread> audio_thread_;
-  media::ScopedAudioManagerPtr audio_manager_;
+  std::unique_ptr<media::AudioManager> audio_manager_;
 
   std::unique_ptr<media::midi::MidiManager> midi_manager_;