Update comments in the Native Messaging example

The comments were not updated when the code changed, so they were
confusing.

R=kalman@chromium.org

Review URL: https://codereview.chromium.org/138133015

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@248625 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 248625
Removes some dead tab related code

No longer needed since non-aura is gone.

BUG=330735
TEST=none
R=ben@chromium.org

Review URL: https://codereview.chromium.org/145103005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@248626 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 248626