Revert of Mojo JS bindings: switch most usage of "connection"/"router" module to "bindings".

extensions/renderer/resources/mime_handler_private_custom_bindings.js

Index: extensions/renderer/resources/mime_handler_private_custom_bindings.js
diff --git a/extensions/renderer/resources/mime_handler_private_custom_bindings.js b/extensions/renderer/resources/mime_handler_private_custom_bindings.js
index 1fa036638db69c505843fac17fc5c44f4e616ed9..4a515394d1413698e119a165be108867743576de 100644
--- a/extensions/renderer/resources/mime_handler_private_custom_bindings.js
+++ b/extensions/renderer/resources/mime_handler_private_custom_bindings.js
@@ -15,11 +15,13 @@
 var servicePromise = Promise.all([
     requireAsync('content/public/renderer/frame_interfaces'),
     requireAsync('extensions/common/api/mime_handler.mojom'),
+    requireAsync('mojo/public/js/router'),
 ]).then(function(modules) {
   var frameInterfaces = modules[0];
   var mojom = modules[1];
-  return new mojom.MimeHandlerServicePtr(
-      frameInterfaces.getInterface(mojom.MimeHandlerService.name));
+  var routerModule = modules[2];
+  return new mojom.MimeHandlerService.proxyClass(new routerModule.Router(
+      frameInterfaces.getInterface(mojom.MimeHandlerService.name)));
 });
 
 // Stores a promise to the GetStreamInfo() result to avoid making additional