Use the ReloadBypassingCache policy

This CL makes use of the new ReloadBypassingCache policy and removes the
setting of cache HTTP headers in blink.

BUG=376025

Review URL: https://codereview.chromium.org/318673002

git-svn-id: svn://svn.chromium.org/blink/trunk@175515 bbb929c8-8fbe-4397-9dbb-9b2b20218538