[Media Router] Add experiment control logic.

chrome/browser/chrome_content_browser_client.cc

Index: chrome/browser/chrome_content_browser_client.cc
diff --git a/chrome/browser/chrome_content_browser_client.cc b/chrome/browser/chrome_content_browser_client.cc
index a9c79916295aebbe951282d1dd1d33ce3c33d9ba..cad0ea87ed7d1403ba440d574f79f556e6f14ed7 100644
--- a/chrome/browser/chrome_content_browser_client.cc
+++ b/chrome/browser/chrome_content_browser_client.cc
@@ -269,6 +269,7 @@
 #endif
 
 #if defined(ENABLE_MEDIA_ROUTER)
+#include "chrome/browser/media/router/media_router_feature.h"
 #include "chrome/browser/media/router/presentation_service_delegate_impl.h"
 #endif
 
@@ -2616,7 +2617,7 @@ content::PresentationServiceDelegate*
 ChromeContentBrowserClient::GetPresentationServiceDelegate(
       content::WebContents* web_contents) {
 #if defined(ENABLE_MEDIA_ROUTER)
-  if (switches::MediaRouterEnabled() &&
+  if (media_router::MediaRouterEnabled() &&
       !web_contents->GetBrowserContext()->IsOffTheRecord()) {
     return media_router::PresentationServiceDelegateImpl::
         GetOrCreateForWebContents(web_contents);