Experimentally strictify third-party cookie blocking.

Experimentally strictify third-party cookie blocking.

This CL turns on strict third-party cookie blocking by forcing the inclusion of
the `kBlockReadingThirdPartyCookies` command-line flag. The goal is to determine
the effect of a change in cookie-blocking behavior; if we Break The Web™ for
Canary users, we'll drop it. If not, we'll re-evaluate the default behavior of
the `kBlockThirdPartyCookies` pref.

I intend to revert this change after a few Canary cycles.

BUG=98241
TEST=Start Chrome. Is the command-line flag set?


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=103112

[jochen (gone - plz use gerrit), 2011-09-28 09:52:58]

LGTM

[commit-bot: I haz the power, 2011-09-28 11:52:38]

CQ is trying tha patch. Follow status at
https://chromium-status.appspot.com/cq/mkwst@chromium.org/8060030/1

[commit-bot: I haz the power, 2011-09-28 13:49:56]

Change committed as 103112