Fix potential unprotected use of handle in Windows event handler.

Source: github.com --- Monday, January 30, 2017
Fix potential unprotected use of handle in Windows event handler. The lock should be held across the use of handle_. Attempt to resolve #28523. R=rmacnak@google.com Review-Url: http://ift.tt/2kMldQN . ...

from Windows http://ift.tt/2kO4IzF