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

content/shell/browser/shell_browser_context.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 "content/shell/browser/shell_browser_context.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/environment.h"
 #include "base/file_util.h"
@@ skipping 31 matching lines @@
   virtual net::URLRequestContext* GetRequestContext() OVERRIDE {
     CHECK(getter_);
     return getter_->GetURLRequestContext();
   }
   virtual bool AllowMicAccess(const GURL& origin) OVERRIDE {
     return false;
   }
   virtual bool AllowCameraAccess(const GURL& origin) OVERRIDE {
     return false;
   }
+  virtual std::string GetMediaDeviceIDSalt() OVERRIDE {
+    return "shell_salt";
+  }
 
   void set_url_request_context_getter(ShellURLRequestContextGetter* getter) {
     getter_ = getter;
   }
 
  private:
   ShellURLRequestContextGetter* getter_;
 
   DISALLOW_COPY_AND_ASSIGN(ShellResourceContext);
 };
@@ skipping 152 matching lines @@
 GeolocationPermissionContext*
     ShellBrowserContext::GetGeolocationPermissionContext()  {
   return NULL;
 }
 
 quota::SpecialStoragePolicy* ShellBrowserContext::GetSpecialStoragePolicy() {
   return NULL;
 }
 
 }  // namespace content