Move chromeos code to namespace chromeos.

Move chromeos code to namespace chromeos.
BUG=none
TEST=none

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=30541

[sky, 2009-10-30 00:19:16]

LGTM with the following change.

http://codereview.chromium.org/341044/diff/1/26
File chrome/browser/chromeos/browser_extenders.cc (right):

http://codereview.chromium.org/341044/diff/1/26#newcode28
Line 28: namespace chromeos {
This should remain in an anonymous name space.