[Reland] [Media Router Tests] Add tests for MediaRouterFactory.

chrome/browser/media/router/media_router_factory.h

Index: chrome/browser/media/router/media_router_factory.h
diff --git a/chrome/browser/media/router/media_router_factory.h b/chrome/browser/media/router/media_router_factory.h
index 4bfac5613b9f5f1e538519ecc42856266d840d97..81d8c9aa6d861202ce470f53f6d6e9516787ec69 100644
--- a/chrome/browser/media/router/media_router_factory.h
+++ b/chrome/browser/media/router/media_router_factory.h
@@ -5,6 +5,7 @@
 #ifndef CHROME_BROWSER_MEDIA_ROUTER_MEDIA_ROUTER_FACTORY_H_
 #define CHROME_BROWSER_MEDIA_ROUTER_MEDIA_ROUTER_FACTORY_H_
 
+#include "base/gtest_prod_util.h"
 #include "base/lazy_instance.h"
 #include "base/macros.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
@@ -30,10 +31,15 @@ class MediaRouterFactory : public BrowserContextKeyedServiceFactory {
 
  private:
   friend struct base::DefaultLazyInstanceTraits<MediaRouterFactory>;
+  FRIEND_TEST_ALL_PREFIXES(MediaRouterFactoryTest,
+                           OffTheRecordBrowserContextShutdown);
 
   MediaRouterFactory();
   ~MediaRouterFactory() override;
 
+  // Exposed for testing.
+  static MediaRouterFactory* GetMediaRouterFactoryForTest();
+
   // BrowserContextKeyedServiceFactory interface.
   content::BrowserContext* GetBrowserContextToUse(
       content::BrowserContext* context) const override;