[GCM] Move the manifest key checking logic to gcm.register function

We should only require the manifest key for gcm.register. A meaningful
error should also be returned.

BUG=344027
TEST=tests updated and new test added

Review URL: https://codereview.chromium.org/167063004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251535 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 251535
Don't raise for GYP_GENERATORS=dump_dependency_json, don't warn when using gyp_env

R=thakis@chromium.org

Review URL: https://codereview.chromium.org/167943002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251536 0039d316-1c4b-4281-b951-d872f2087c98
InstantExtended: assign all cacheable NTPs to the same process.

BUG=333397

Review URL: https://codereview.chromium.org/135383002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251537 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 251537