[Mojo Video Capture] Fix VideoCaptureManager exposing implementation details to clients

content/browser/browser_main_loop.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/browser_main_loop.h"
 
 #include <stddef.h>
 
 #include <string>
 #include <utility>
@@ skipping 1498 matching lines @@
     GetContentClient()->browser()->ResourceDispatcherHostCreated();
 
     loader_delegate_.reset(new LoaderDelegateImpl());
     resource_dispatcher_host_->SetLoaderDelegate(loader_delegate_.get());
   }
 
   // MediaStreamManager needs the IO thread to be created.
   {
     TRACE_EVENT0("startup",
       "BrowserMainLoop::BrowserThreadsStarted:InitMediaStreamManager");
-    media_stream_manager_.reset(new MediaStreamManager(audio_system_.get()));
+    media_stream_manager_ =
+        MediaStreamManager::CreateWithDefaults(audio_system_.get());
   }
 
   {
     TRACE_EVENT0("startup",
       "BrowserMainLoop::BrowserThreadsStarted:InitSpeechRecognition");
     speech_recognition_manager_.reset(new SpeechRecognitionManagerImpl(
         audio_system_.get(), audio_manager_.get(),
         media_stream_manager_.get()));
   }
 
@@ skipping 243 matching lines @@
         BrowserThread::GetTaskRunnerForThread(BrowserThread::FILE),
         MediaInternals::GetInstance());
   }
   CHECK(audio_manager_);
 
   audio_system_ = media::AudioSystemImpl::Create(audio_manager_.get());
   CHECK(audio_system_);
 }
 
 }  // namespace content