Make all the files mapped in when running net_unittests read only.

This means no file can be opened for write during the test run.

R=vadimsh@chromium.org
BUG=116251
NOTRY=true

Review URL: https://codereview.chromium.org/133823003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249500 0039d316-1c4b-4281-b951-d872f2087c98
1 file changed