Implement a salt for MediaSource IDs that can be cleared by a user.

content/public/browser/content_browser_client.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/content_browser_client.h"
 
 #include "base/files/file_path.h"
 #include "ui/gfx/image/image_skia.h"
 #include "url/gurl.h"
 
@@ skipping 243 matching lines @@
 }
 
 base::FilePath ContentBrowserClient::GetDefaultDownloadDirectory() {
   return base::FilePath();
 }
 
 std::string ContentBrowserClient::GetDefaultDownloadName() {
   return std::string();
 }
 
+std::string ContentBrowserClient::GetDeviceIdSalt(ResourceContext* rc) {
+  return std::string();
+}
+
 BrowserPpapiHost*
     ContentBrowserClient::GetExternalBrowserPpapiHost(int plugin_process_id) {
   return NULL;
 }
 
 bool ContentBrowserClient::SupportsBrowserPlugin(
     BrowserContext* browser_context, const GURL& site_url) {
   return false;
 }
 
@@ skipping 27 matching lines @@
 }
 #endif
 
 bool ContentBrowserClient::IsPluginAllowedToCallRequestOSFileHandle(
     content::BrowserContext* browser_context,
     const GURL& url) {
   return false;
 }
 
 }  // namespace content