GitLab

From mac's fsync man page:

For applications that require tighter guarantees about the integrity of their
data, Mac OS X provides the F_FULLFSYNC fcntl.  The F_FULLFSYNC fcntl asks the
drive to flush all buffered data to permanent storage.  Applications, such as
databases, that require a strict ordering of writes should use F_FULLFSYNC to
ensure that their data is written in the order they expect.

Also, specifically check for a return value of -1 from fdatasync. mac's fcntl
only guarantees to return -1 on error and something other than -1 on success.
All other platforms agree to return -1 on error for fsync/fdatasync/_commit.

Review URL: https://chromiumcodereview.appspot.com/23549017

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@221413 0039d316-1c4b-4281-b951-d872f2087c98