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

content/browser/resource_context_impl.cc

 // 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.
 
 #include "content/browser/resource_context_impl.h"
 
 #include "base/logging.h"
 #include "content/browser/fileapi/chrome_blob_storage_context.h"
 #include "content/browser/host_zoom_map_impl.h"
 #include "content/browser/loader/resource_dispatcher_host_impl.h"
@@ skipping 37 matching lines @@
   ResourceDispatcherHostImpl* rdhi = ResourceDispatcherHostImpl::Get();
   if (rdhi) {
     rdhi->CancelRequestsForContext(this);
     rdhi->RemoveResourceContext(this);
   }
 
   // In some tests this object is destructed on UI thread.
   DetachUserDataThread();
 }
 
+std::string ResourceContext::GetMediaDeviceIDSalt() {
+  return std::string();
+}
+
 scoped_ptr<net::ClientCertStore> ResourceContext::CreateClientCertStore() {
   return scoped_ptr<net::ClientCertStore>();
 }
 
 ChromeBlobStorageContext* GetChromeBlobStorageContextForResourceContext(
     ResourceContext* resource_context) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   return UserDataAdapter<ChromeBlobStorageContext>::Get(
       resource_context, kBlobStorageContextKeyName);
 }
@@ skipping 40 matching lines @@
   // store a non-owning pointer here.
   resource_context->SetUserData(
       kHostZoomMapKeyName,
       new NonOwningZoomData(
           HostZoomMap::GetForBrowserContext(browser_context)));
 
   resource_context->DetachUserDataThread();
 }
 
 }  // namespace content