Show Media Router toolbar icon ephemerally for MR dialogs

chrome/browser/ui/webui/media_router/media_router_test.h

 // Copyright 2015 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 CHROME_BROWSER_UI_WEBUI_MEDIA_ROUTER_MEDIA_ROUTER_TEST_H_
 #define CHROME_BROWSER_UI_WEBUI_MEDIA_ROUTER_MEDIA_ROUTER_TEST_H_
 
 #include "base/macros.h"
 #include "chrome/test/base/browser_with_test_window_test.h"
 #include "extensions/common/feature_switch.h"
 
 class BrowserWindow;
+class TestingProfile;
 
 class MediaRouterTest : public BrowserWithTestWindowTest {
  public:
+  // |require_mock_ui_service_| defaults to false in the default ctor.
   MediaRouterTest();
+  explicit MediaRouterTest(bool require_mock_ui_service);
   ~MediaRouterTest() override;
 
+  // BrowserWithTestWindowTest:
+  TestingProfile* CreateProfile() override;
+
  protected:
   // BrowserWithTestWindowTest override.
   BrowserWindow* CreateBrowserWindow() override;
 
  private:
   extensions::FeatureSwitch::ScopedOverride feature_override_;
+
+  // When this is set to true, MockMediaRouterUIService is instantiated.
+  // Otherwise, no MediaRouterUIService is instantiated.
+  bool require_mock_ui_service_;
+
   DISALLOW_COPY_AND_ASSIGN(MediaRouterTest);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_MEDIA_ROUTER_MEDIA_ROUTER_TEST_H_