[Chromecast] Cleanup the API for creating MediaPipelineBackend.

chromecast/browser/cast_content_browser_client.cc

Index: chromecast/browser/cast_content_browser_client.cc
diff --git a/chromecast/browser/cast_content_browser_client.cc b/chromecast/browser/cast_content_browser_client.cc
index 744e66d70fdae76c8b79a18b8e47036bb26c6fd2..20c4361633dd5237f09220e2fe52489a22ec6a3c 100644
--- a/chromecast/browser/cast_content_browser_client.cc
+++ b/chromecast/browser/cast_content_browser_client.cc
@@ -80,18 +80,12 @@ scoped_ptr<CastService> CastContentBrowserClient::CreateCastService(
   return make_scoped_ptr(new CastServiceSimple(browser_context, pref_service));
 }
 
+#if !defined(OS_ANDROID)
 scoped_ptr<::media::AudioManagerFactory>
 CastContentBrowserClient::CreateAudioManagerFactory() {
-#if defined(OS_ANDROID)
-  // Return nullptr. The factory will not be set, and the default
-  // implementation of AudioManager will be used.
-  return scoped_ptr<::media::AudioManagerFactory>();
-#else
   return make_scoped_ptr(new media::CastAudioManagerFactory());
-#endif
 }
 
-#if !defined(OS_ANDROID)
 scoped_refptr<media::CmaMediaPipelineClient>
 CastContentBrowserClient::CreateCmaMediaPipelineClient() {
   return make_scoped_refptr(new media::CmaMediaPipelineClient());
@@ -101,7 +95,7 @@ scoped_ptr<::media::BrowserCdmFactory>
 CastContentBrowserClient::CreateBrowserCdmFactory() {
   return make_scoped_ptr(new media::CastBrowserCdmFactory());
 }
-#endif
+#endif  // OS_ANDROID
 
 void CastContentBrowserClient::ProcessExiting() {
   // Finalize CastMediaShlib on media thread to ensure it's not accessed
@@ -124,9 +118,8 @@ bool CastContentBrowserClient::EnableRemoteDebuggingImmediately() {
 
 content::BrowserMainParts* CastContentBrowserClient::CreateBrowserMainParts(
     const content::MainFunctionParams& parameters) {
-  content::BrowserMainParts* parts = new CastBrowserMainParts(
-      parameters, url_request_context_factory_.get(),
-      CreateAudioManagerFactory());
+  content::BrowserMainParts* parts =
+      new CastBrowserMainParts(parameters, url_request_context_factory_.get());
   CastBrowserProcess::GetInstance()->SetCastContentBrowserClient(this);
   return parts;
 }