[Mac] Disable the Encoding menu within the Wrench menu for Chromium-internal pages.
[Mac] Disable the Encoding menu within the Wrench menu for Chromium-internal pages.

BUG=48157
TEST=Go to about:version or the NTP. Open Wrench-->Tools-->Encoding. All items are disabled.

Review URL: http://codereview.chromium.org/2928001

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@51860 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