GitLab

In preparation for removing GetFileInfoByPath(), which is a synchronous
function. The new function is not used in production code yet.

BUG=chromium-os:30066
TEST=add unit tests

Review URL: https://chromiumcodereview.appspot.com/10270018

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@134589 0039d316-1c4b-4281-b951-d872f2087c98