Mojo: Add BindingsSupportImpl on top of HandleWatcher

mojo/common/handle_watcher.h

Index: mojo/common/handle_watcher.h
diff --git a/mojo/common/handle_watcher.h b/mojo/common/handle_watcher.h
index 8e04aa707e2a4803f80655a03e319e5ec5b846b4..a6a73ea6c1ee9f3b5bb5e44d0d706652d0841a7e 100644
--- a/mojo/common/handle_watcher.h
+++ b/mojo/common/handle_watcher.h
@@ -38,7 +38,7 @@ class MOJO_COMMON_EXPORT HandleWatcher {
   void Start(MojoHandle handle,
              MojoWaitFlags wait_flags,
              MojoDeadline deadline,
-             const base::Closure& callback);
+             const base::Callback<void(MojoResult)>& callback);
 
   // Stops listening. Does nothing if not in the process of listening.
   void Stop();
@@ -54,7 +54,7 @@ class MOJO_COMMON_EXPORT HandleWatcher {
   struct StartState;
 
   // See description of |StartState::weak_factory| for details.
-  void OnHandleReady();
+  void OnHandleReady(MojoResult result);
 
   // If non-NULL Start() has been invoked.
   scoped_ptr<StartState> start_state_;