GitLab

This ancient CL suggested a simplication in mapped_file_posix.cc:
https://codereview.chromium.org/160288

After hitting this DCHECK on an embedded device where using a debugger
is difficult, I decided to make the suggested change and add some useful
logging while I was at it.

BUG=391937

Review URL: https://codereview.chromium.org/372113003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@281747 0039d316-1c4b-4281-b951-d872f2087c98