[Media Router] Add integration browser tests

chrome/test/media_router/media_router_base_browsertest.h

Index: chrome/test/media_router/media_router_base_browsertest.h
diff --git a/chrome/test/media_router/media_router_base_browsertest.h b/chrome/test/media_router/media_router_base_browsertest.h
index cbfc9e52a1da27d8c1d6406069e7c96c3a1257b6..ab63b7808168a426eded5ae2e07029621ccd0fd8 100644
--- a/chrome/test/media_router/media_router_base_browsertest.h
+++ b/chrome/test/media_router/media_router_base_browsertest.h
@@ -43,8 +43,8 @@ class MediaRouterBaseBrowserTest : public ExtensionBrowserTest,
   void SetUpOnMainThread() override;
   void TearDownOnMainThread() override;
 
-  void InstallAndEnableMRExtension();
-  void UninstallMRExtension();
+  virtual void InstallAndEnableMRExtension();
+  virtual void UninstallMRExtension();
 
   virtual void ParseCommandLine();
 
@@ -61,14 +61,15 @@ class MediaRouterBaseBrowserTest : public ExtensionBrowserTest,
   // Wait for a specific time.
   void Wait(base::TimeDelta timeout);
 
-  bool is_unpacked() const { return !extension_unpacked_.empty(); }
-
   bool is_extension_host_created() const { return extension_host_created_; }
 
   bool is_incognito() { return profile()->IsOffTheRecord(); }
 
-  // These values are initialized via flags.
-  base::FilePath extension_crx_;
+  // Returns the superclass' browser(). Marked virtual so that it can be
+  // overridden by MediaRouterIntegrationIncognitoBrowserTest.
+  virtual Browser* browser();
+
+  // |extension_unpacked_| is initialized via a flag.
   base::FilePath extension_unpacked_;
 
   base::WaitableEvent extension_load_event_;