Cleanup webview app_shell_browsertests and add webview media permission tests in app_shell_browsert…

extensions/browser/guest_view/web_view/web_view_media_access_apitest.h

+// Copyright 2014 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 "extensions/browser/guest_view/web_view/web_view_apitest.h"
+
+namespace extensions {
+
+class WebViewMediaAccessAPITest : public WebViewAPITest {
+ protected:
+  WebViewMediaAccessAPITest();
+
+  // Runs media_access/allow tests.
+  void RunTest(const std::string& test_name);
+
+  // content::BrowserTestBase implementation
+  virtual void SetUpOnMainThread() override;
+  virtual void TearDownOnMainThread() override;
+};
+
+}  // namespace extensions