Fake PO2TS GetRequestContext should return NULL.

The fake PO2TS does not actually use the request context. This CL overrides the
GetRequestContext() in PO2TS and returns NULL to avoid errors like the ones
explained at (that occur on iOS)
https://groups.google.com/a/chromium.org/forum/#!msg/chromium-dev/HWdp5roPpF4/j7drB1WW01EJ

BUG=NONE

Review URL: https://codereview.chromium.org/166573002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251341 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 251341
Copies DockInfoGtk into WindowFinder.

I'm going to nuke DockInfo soonish. This is a stup in that
direction.

BUG=none
TEST=none
R=erg@chromium.org

Review URL: https://codereview.chromium.org/165463003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251342 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 251342