Fix the flaky crash in FileBrowseBrowserTest.InputFileTriggerFileBrowse
Fix the flaky crash in FileBrowseBrowserTest.InputFileTriggerFileBrowse

CheckFileBrowseClosed could crash if the delayed execution happens after
FileBrowse popup is destroied. Change the wait to use notification.

BUG=none
TEST=FileBrowseBrowserTest.InputFileTriggerFileBrowse should not crash.

Review URL: http://codereview.chromium.org/2006013

git-svn-id: http://src.chromium.org/svn/trunk/src@47089 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: a70ec8db7a22f29ef2b350041fee9a617491b323
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser