Set the AudioManager factory before the browser main loop.

chromecast/browser/cast_browser_main_parts.h

Index: chromecast/browser/cast_browser_main_parts.h
diff --git a/chromecast/browser/cast_browser_main_parts.h b/chromecast/browser/cast_browser_main_parts.h
index 7c9baf49ad79fddd853d9e3d89093edf19d4f489..49954cef55d7192bec9174008058f97684b0478e 100644
--- a/chromecast/browser/cast_browser_main_parts.h
+++ b/chromecast/browser/cast_browser_main_parts.h
@@ -11,6 +11,10 @@
 #include "content/public/browser/browser_main_parts.h"
 #include "content/public/common/main_function_params.h"
 
+namespace media {
+class AudioManagerFactory;
+}
+
 namespace chromecast {
 namespace shell {
 class CastBrowserProcess;
@@ -18,9 +22,11 @@ class URLRequestContextFactory;
 
 class CastBrowserMainParts : public content::BrowserMainParts {
  public:
+  // This class does not take ownership of |url_request_content_factory|.
   CastBrowserMainParts(
       const content::MainFunctionParams& parameters,
-      URLRequestContextFactory* url_request_context_factory);
+      URLRequestContextFactory* url_request_context_factory,
+      scoped_ptr<::media::AudioManagerFactory> audio_manager_factory);
   ~CastBrowserMainParts() override;
 
   // content::BrowserMainParts implementation:
@@ -35,6 +41,7 @@ class CastBrowserMainParts : public content::BrowserMainParts {
   scoped_ptr<CastBrowserProcess> cast_browser_process_;
   const content::MainFunctionParams parameters_;  // For running browser tests.
   URLRequestContextFactory* const url_request_context_factory_;
+  scoped_ptr<::media::AudioManagerFactory> audio_manager_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(CastBrowserMainParts);
 };