Unlink corrupt SimpleCache index files immediately after load.
The crash on startup in the referenced bug is very bad in part because
the corrupt index which caused it is left on disk, so all startups
until user data is cleared will crash. For maximum safety, we should
unlink the index file ASAP after finding it is corrupt.
R=rdsmith@chromium.org
BUG=251465
Review URL: https://codereview.chromium.org/
17265007
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@207813 0039d316-1c4b-4281-b951-d872f2087c98