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

content/public/browser/content_browser_client.h

 // 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.
 
 #ifndef CONTENT_PUBLIC_BROWSER_CONTENT_BROWSER_CLIENT_H_
 #define CONTENT_PUBLIC_BROWSER_CONTENT_BROWSER_CLIENT_H_
 
 #include <map>
 #include <string>
 #include <utility>
@@ skipping 506 matching lines @@
   virtual void ClearCookies(RenderViewHost* rvh) {}
 
   // Returns the default download directory.
   // This can be called on any thread.
   virtual base::FilePath GetDefaultDownloadDirectory();
 
   // Returns the default filename used in downloads when we have no idea what
   // else we should do with the file.
   virtual std::string GetDefaultDownloadName();
 
+  // Returns a random salt string that is used for creating MediaSourceIDs.
+  // The salt should be stored in the current user profile and should be reset
+  // if cookies are cleared. This is called on the IO thread.
+  virtual std::string GetMediaDeviceIDSalt(ResourceContext* rc);

[jam, 2013/11/04 15:38:53]

since this method is invoked per ResourceContext, it should be moved to be on
ResourceContext

[perkj_chrome, 2013/11/04 19:05:38]

ok- done. 

+
   // Notification that a pepper plugin has just been spawned. This allows the
   // embedder to add filters onto the host to implement interfaces.
   // This is called on the IO thread.
   virtual void DidCreatePpapiPlugin(BrowserPpapiHost* browser_host) {}
 
   // Gets the host for an external out-of-process plugin.
   virtual content::BrowserPpapiHost* GetExternalBrowserPpapiHost(
       int plugin_child_id);
 
   // Returns true if the given browser_context and site_url support hosting
@@ skipping 65 matching lines @@
   // Returns true if plugin referred to by the url can use
   // pp::FileIO::RequestOSFileHandle.
   virtual bool IsPluginAllowedToCallRequestOSFileHandle(
       content::BrowserContext* browser_context,
       const GURL& url);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_CONTENT_BROWSER_CLIENT_H_