Branded stable channel builds should not display any text after the version number in the About window or about:version.
Branded stable channel builds should not display any text after the version
number in the About window or about:version.

The existing code assumed that KSChannelID would be set to "stable" on the
stable channel, but this is incorrect. On the stable channel, KSChannelID is
not set at all.

Originally, the code was correct, but it broke in r36375.

BUG=43357
TEST=1. Check the About window in a stable-channel build. It should show the
        version number without being adorned by the word "unknown" or any
        other text.
     2. In the same stable-channel builds, visit about:version. The Google
        Chrome line should show something like 5.0.375.29 (Official Build
        46008) without the word "unknown" or any other text.
Review URL: http://codereview.chromium.org/1990002

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@46541 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser