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

Index: chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_api.cc
diff --git a/chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_api.cc b/chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_api.cc
index 654a698285a1cadd30bd61509a6739c9bf262bc0..eb0854a4170af764ebe77a816c1bf48a1af4d4a7 100644
--- a/chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_api.cc
+++ b/chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_api.cc
@@ -293,6 +293,7 @@ void WebrtcAudioPrivateGetAssociatedSinkFunction::OnGetDevicesDone() {
                  GetRawSourceIDOnIOThread,
                  this,
                  GURL(params_->security_origin),
+                 GetProfile()->GetResourceContext(),

[Jói, 2013/12/02 10:05:53]

nit: I would group the two explicit parameters together, so either pass the
ResourceContext first or last, not between the two parameters.

[perkj_chrome, 2013/12/02 13:26:48]

Done.

                  params_->source_id_in_origin),
       base::Bind(
           &WebrtcAudioPrivateGetAssociatedSinkFunction::OnGetRawSourceIDDone,
@@ -301,7 +302,9 @@ void WebrtcAudioPrivateGetAssociatedSinkFunction::OnGetDevicesDone() {
 
 std::string
 WebrtcAudioPrivateGetAssociatedSinkFunction::GetRawSourceIDOnIOThread(
-    GURL security_origin, const std::string& source_id_in_origin) {
+    GURL security_origin,
+    content::ResourceContext* context,
+    const std::string& source_id_in_origin) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 
   // Find the raw source ID for source_id_in_origin.
@@ -311,7 +314,10 @@ WebrtcAudioPrivateGetAssociatedSinkFunction::GetRawSourceIDOnIOThread(
        ++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;