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

content/public/browser/web_contents_delegate.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/public/browser/web_contents_delegate.h"
 
 #include "base/compiler_specific.h"
 #include "base/logging.h"
 #include "base/memory/singleton.h"
 #include "build/build_config.h"
@@ skipping 183 matching lines @@
 
 bool WebContentsDelegate::CheckMediaAccessPermission(
     WebContents* web_contents,
     const GURL& security_origin,
     MediaStreamType type) {
   LOG(ERROR) << "WebContentsDelegate::CheckMediaAccessPermission: "
              << "Not supported.";
   return false;
 }
 
+std::string WebContentsDelegate::GetDefaultMediaDeviceId(
+    WebContents* web_contents,
+    MediaStreamType type) {
+  return std::string();
+}
+
 #if defined(OS_ANDROID)
 void WebContentsDelegate::RequestMediaDecodePermission(
     WebContents* web_contents,
     const base::Callback<void(bool)>& callback) {
   callback.Run(false);
 }
 
 base::android::ScopedJavaLocalRef<jobject>
 WebContentsDelegate::GetContentVideoViewEmbedder() {
   return base::android::ScopedJavaLocalRef<jobject>();
@@ skipping 52 matching lines @@
 void WebContentsDelegate::ShowCertificateViewerInDevTools(
     WebContents* web_contents,
     scoped_refptr<net::X509Certificate> certificate) {
 }
 
 void WebContentsDelegate::RequestAppBannerFromDevTools(
     content::WebContents* web_contents) {
 }
 
 }  // namespace content