Add functionality to get default media device IDs from user preferences.

content/browser/frame_host/render_frame_host_delegate.cc

 // Copyright 2013 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 <stddef.h>
 
 #include "base/callback.h"
 #include "base/strings/string16.h"
 #include "build/build_config.h"
 #include "content/browser/frame_host/render_frame_host_delegate.h"
@@ skipping 39 matching lines @@
 }
 
 bool RenderFrameHostDelegate::CheckMediaAccessPermission(
     const GURL& security_origin,
     MediaStreamType type) {
   LOG(ERROR) << "RenderFrameHostDelegate::CheckMediaAccessPermission: "
              << "Not supported.";
   return false;
 }
 
+std::string RenderFrameHostDelegate::GetDefaultMediaDeviceId(
+    MediaStreamType type) {
+  return std::string();
+}
+
 AccessibilityMode RenderFrameHostDelegate::GetAccessibilityMode() const {
   return AccessibilityModeOff;
 }
 
 RenderFrameHost* RenderFrameHostDelegate::GetGuestByInstanceID(
     RenderFrameHost* render_frame_host,
     int browser_plugin_instance_id) {
   return NULL;
 }
 
@@ skipping 17 matching lines @@
     SiteInstance* source_site_instance) const {
   return false;
 }
 
 std::unique_ptr<WebUIImpl>
 RenderFrameHostDelegate::CreateWebUIForRenderFrameHost(const GURL& url) {
   return nullptr;
 }
 
 }  // namespace content