Log more info in file_util::WriteFile for debugging.

This is intended to be a temporary change.

TBR=willchan

BUG=329478

Review URL: https://codereview.chromium.org/100033005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241538 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241538