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 274 matching lines @@
 }
 
 void WebrtcAudioPrivateGetAssociatedSinkFunction::OnGetDevicesDone() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   BrowserThread::PostTaskAndReplyWithResult(
       BrowserThread::IO,
       FROM_HERE,
       base::Bind(&WebrtcAudioPrivateGetAssociatedSinkFunction::
                  GetRawSourceIDOnIOThread,
                  this,
+                 GetProfile()->GetResourceContext(),
                  GURL(params_->security_origin),
                  params_->source_id_in_origin),
       base::Bind(
           &WebrtcAudioPrivateGetAssociatedSinkFunction::OnGetRawSourceIDDone,
           this));
 }
 
 std::string
 WebrtcAudioPrivateGetAssociatedSinkFunction::GetRawSourceIDOnIOThread(
-    GURL security_origin, const std::string& source_id_in_origin) {
+    content::ResourceContext* context,
+    GURL security_origin,
+    const std::string& source_id_in_origin) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 
   // 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(
-            security_origin, source_id_in_origin, id)) {
+            context,
+            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;
     }
   }
 
   return raw_source_id;
 }
 
@@ skipping 29 matching lines @@
 void WebrtcAudioPrivateGetAssociatedSinkFunction::OnGetAssociatedSinkDone(
     const std::string& associated_sink_id) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   results_.reset(
       wap::GetAssociatedSink::Results::Create(associated_sink_id).release());
   SendResponse(true);
 }
 
 }  // namespace extensions