Add CastMediaBlocker and BrowserTest

chromecast/browser/test/chromecast_browser_test_helper.h

 // Copyright 2016 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.
 
 #ifndef CHROMECAST_BROWSER_TEST_CHROMECAST_BROWSER_TEST_HELPER_H_
 #define CHROMECAST_BROWSER_TEST_CHROMECAST_BROWSER_TEST_HELPER_H_
 
 #include <memory>
 
 class GURL;
 
 namespace content {
 class WebContents;
 }
 
 namespace chromecast {
 namespace shell {
 
 class ChromecastBrowserTestHelper {
  public:
   // Creates an implementation of ChromecastBrowserTestHelper. Allows public
   // and internal builds to instantiate different implementations.
   static std::unique_ptr<ChromecastBrowserTestHelper> Create();
 
   virtual ~ChromecastBrowserTestHelper() {}
   virtual content::WebContents* NavigateToURL(const GURL& url) = 0;
+  virtual void BlockMediaLoading(bool block) = 0;
 };
 
 }  // namespace shell
 }  // namespace chromecast
 
 #endif  // CHROMECAST_BROWSER_TEST_CHROMECAST_BROWSER_TEST_HELPER_H_