[Media Router] Custom Controls 3 - add plumbing through MRUI and MRWebUIMessageHandler

chrome/common/chrome_features.cc

Index: chrome/common/chrome_features.cc
diff --git a/chrome/common/chrome_features.cc b/chrome/common/chrome_features.cc
index 6e36f8bd4ee4aa839ffb59d388c0a78f79a990bc..8d288122b9b23739a848dd3d255a711f4731b769 100644
--- a/chrome/common/chrome_features.cc
+++ b/chrome/common/chrome_features.cc
@@ -209,6 +209,12 @@ const base::Feature kMediaRemoting{"MediaRemoting",
                                    base::FEATURE_DISABLED_BY_DEFAULT};
 const base::Feature kMediaRemotingEncrypted{"MediaRemotingEncrypted",
                                             base::FEATURE_DISABLED_BY_DEFAULT};
+
+// If enabled, replaces the <extensionview> controller in the route details view
+// of the Media Router dialog with the controller bundled with the WebUI
+// resources.
+const base::Feature kMediaRouterUIRouteController{
+    "MediaRouterUIRouteController", base::FEATURE_DISABLED_BY_DEFAULT};
 #endif  // !defined(OS_ANDROID) && !defined(OS_IOS)
 
 // Enables or disables modal permission prompts.