Fix webrtcAudioPrivate API to handle requests from <webview>s.

content/browser/renderer_host/render_process_host_impl.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.
 
 // Represents the browser side of the browser <--> renderer communication
 // channel. There will be one RenderProcessHost per renderer process.
 
 #include "content/browser/renderer_host/render_process_host_impl.h"
 
 #include <algorithm>
@@ skipping 2365 matching lines @@
 }
 
 void RenderProcessHostImpl::DecrementWorkerRefCount() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   DCHECK_GT(worker_ref_count_, 0);
   --worker_ref_count_;
   if (worker_ref_count_ == 0)
     Cleanup();
 }
 
+void RenderProcessHostImpl::GetAudioOutputControllers(
+    const GetAudioOutputControllersCallback& callback) const {
+  audio_renderer_host()->GetOutputControllers(callback);
+}
+
 }  // namespace content