Remove enable_media_router.

chrome/browser/extensions/BUILD.gn

Index: chrome/browser/extensions/BUILD.gn
diff --git a/chrome/browser/extensions/BUILD.gn b/chrome/browser/extensions/BUILD.gn
index a47d285c67b39656a18275ecbfc2894b88348a98..1fdf93bf9a1580cb8ebbb45d7b41ff24fabbae6e 100644
--- a/chrome/browser/extensions/BUILD.gn
+++ b/chrome/browser/extensions/BUILD.gn
@@ -813,6 +813,7 @@ static_library("extensions") {
     "//chrome/app/theme:theme_resources",
     "//chrome/app/vector_icons",
     "//chrome/browser/devtools",
+    "//chrome/browser/media/router",
     "//chrome/browser/media/router/discovery",
     "//chrome/common",
     "//chrome/common/extensions/api:api_registration",
@@ -918,10 +919,6 @@ static_library("extensions") {
     "//url",
   ]
 
-  if (enable_media_router) {
-    deps += [ "//chrome/browser/media/router" ]
-  }
-
   if (!is_chromeos) {
     sources += [ "chrome_kiosk_delegate.cc" ]
   }