update_engine: Add locations to the MessageLoop calls.

When running the unittests with --v=1, this patch will show the location
where the tasks were posted to the FakeMessageLoop.

BUG=brillo:91
TEST=Ran unittest with --v=1

Change-Id: I0f9b0a3b67a40c26965a396258f1bd45e38f5ba3
Reviewed-on: https://chromium-review.googlesource.com/280568
Tested-by: Alex Deymo <deymo@chromium.org>
Reviewed-by: Alex Vakulenko <avakulenko@chromium.org>
Commit-Queue: Alex Deymo <deymo@chromium.org>
diff --git a/update_manager/update_manager-inl.h b/update_manager/update_manager-inl.h
index 9463c76..b8fef28 100644
--- a/update_manager/update_manager-inl.h
+++ b/update_manager/update_manager-inl.h
@@ -9,6 +9,7 @@
 #include <string>
 
 #include <base/bind.h>
+#include <base/location.h>
 #include <chromeos/message_loops/message_loop.h>
 
 #include "update_engine/update_manager/evaluation_context.h"
@@ -144,7 +145,7 @@
   base::Closure eval_callback = base::Bind(
       &UpdateManager::OnPolicyReadyToEvaluate<R, ExpectedArgs...>,
       base::Unretained(this), ec, callback, policy_method, args...);
-  chromeos::MessageLoop::current()->PostTask(eval_callback);
+  chromeos::MessageLoop::current()->PostTask(FROM_HERE, eval_callback);
 }
 
 }  // namespace chromeos_update_manager