Always use safeCallbackApply to invoke fileSystem API callbacks.
Previously, for API methods where an Entry was provided to the callback,
if the callback throws an exception, it would be printed to the
background page's console. With this change, these exceptions are
reported the same way as those thrown by callbacks to other API methods,
including reporting the call stack to the original call.
BUG=314124
Review URL: https://codereview.chromium.org/
146823005
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@248654 0039d316-1c4b-4281-b951-d872f2087c98