Add more sync calls to try to make the FileWatcher test not flaky on OSX.
Add more sync calls to try to make the FileWatcher test not
flaky on OSX.

BUG=38188

Review URL: http://codereview.chromium.org/1045004

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@41819 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser