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

chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_api.h

 // 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.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_API_WEBRTC_AUDIO_PRIVATE_WEBRTC_AUDIO_PRIVATE_API_H_
 #define CHROME_BROWSER_EXTENSIONS_API_WEBRTC_AUDIO_PRIVATE_WEBRTC_AUDIO_PRIVATE_API_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/system_monitor/system_monitor.h"
 #include "chrome/browser/extensions/api/profile_keyed_api_factory.h"
@@ skipping 135 matching lines @@
   // 3. Given a raw source ID, get the associated sink ID on the
   //    device thread.
 
   // Fills in |source_devices_|. OnGetDevicesDone will be invoked on
   // the UI thread once done.
   void GetDevicesOnDeviceThread();
   void OnGetDevicesDone();
 
   // Takes the parameters of the function, returns the raw source
   // device ID, or the empty string if none.
-  std::string GetRawSourceIDOnIOThread(GURL security_origin,
+  std::string GetRawSourceIDOnIOThread(content::ResourceContext* context,
+                                       GURL security_origin,
                                        const std::string& source_id_in_origin);
   void OnGetRawSourceIDDone(const std::string& raw_source_id);
 
   // Given a raw source ID, get its associated sink, which needs to
   // happen on the device thread.
   std::string GetAssociatedSinkOnDeviceThread(const std::string& raw_source_id);
   void OnGetAssociatedSinkDone(const std::string& associated_sink_id);
 
   // Accessed from UI thread and device thread, but only on one at a
   // time, no locking needed.
   scoped_ptr<api::webrtc_audio_private::GetAssociatedSink::Params> params_;
 
   // Filled in by DoWorkOnDeviceThread.
   media::AudioDeviceNames source_devices_;
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_WEBRTC_AUDIO_PRIVATE_WEBRTC_AUDIO_PRIVATE_API_H_