crosswalk-project/crosswalk — pull request #1834 by sqliu (2014-04-18 02:12:30+00:00)
Title: Add BACK key handler to the XWalkView.

Notify user about the BACK key pressed event, for the first time BACK key
pressed, a toast prompted to notify that once more BACK key pressed will
exit the app.

BUG=https://crosswalk-project.org/jira/browse/XWALK-1131