Add base::RunLoop and update ui_test_utils to use it to reduce flakiness

ui/ui_controls/ui_controls_internal_win.cc

Index: ui/ui_controls/ui_controls_internal_win.cc
diff --git a/ui/ui_controls/ui_controls_internal_win.cc b/ui/ui_controls/ui_controls_internal_win.cc
index 37e0d1aa713b39c9a0812a6f1a7bc35576ca87b5..dc583f43eec97a81e3556e69c745b50aabd25419 100644
--- a/ui/ui_controls/ui_controls_internal_win.cc
+++ b/ui/ui_controls/ui_controls_internal_win.cc
@@ -135,7 +135,10 @@ void InputDispatcher::MatchingMessageFound() {
 }
 
 void InputDispatcher::NotifyTask() {
-  task_.Run();
+  if (!task_.is_null()) {
+    task_.Run();
+    task_.Reset();

[jar (doing other things), 2012/06/08 01:05:37]

Why did this change?

[jbates, 2012/06/13 22:11:20]

I'll undo this.  I just noticed there's a DCHECK in Release if it's called too
many times so no need for this code.

+  }
   Release();
 }