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

chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_api.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 "chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_api.h"
 
 #include "base/lazy_instance.h"
 #include "base/message_loop/message_loop_proxy.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/task_runner_util.h"
@@ skipping 265 matching lines @@
     GURL security_origin, std::string source_id_in_origin) {
   AudioDeviceNames source_devices;
   AudioManager::Get()->GetAudioInputDeviceNames(&source_devices);
 
   // Find the raw source ID for source_id_in_origin.
   std::string raw_source_id;
   for (AudioDeviceNames::const_iterator it = source_devices.begin();
        it != source_devices.end();
        ++it) {
     const std::string& id = it->unique_id;
-    if (content::DoesMediaDeviceIDMatchHMAC(
+    // TODO(perkj): Need the resource context / browser context here.
+    if (content::DoesMediaDeviceIDMatchHMAC(NULL,

[perkj_chrome, 2013/10/31 15:31:48]

help!

[Jói, 2013/10/31 16:14:47]

This object inherits from ExtensionFunction, which provides a GetProfile()
method.

[perkj_chrome, 2013/10/31 17:05:44]

Done.

             security_origin, source_id_in_origin, id)) {
       raw_source_id = id;
       DVLOG(2) << "Found raw ID " << raw_source_id
                << " for source ID in origin " << source_id_in_origin;
       break;
     }
   }
 
   // We return an empty string if there is no associated output device.
   std::string result;
   if (!raw_source_id.empty()) {
     result = AudioManager::Get()->GetAssociatedOutputDeviceID(raw_source_id);
   }
 
   return result;
 }
 
 void WebrtcAudioPrivateGetAssociatedSinkFunction::DoneOnUIThread(
     const std::string& associated_sink_id) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   SetResult(wap::GetAssociatedSink::Results::Create(
       associated_sink_id).release());
   SendResponse(true);
 }
 
 }  // namespace extensions