Unittest gardening.
Unittest gardening.

Enable extension_messages_unittest.cc for Mac and Linux.  Had been
added for Windows, but not to chrome.gyp.

Drop extension_content_script_inject_unittest.cc because it no longer
exists.

Review URL: http://codereview.chromium.org/87070

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@14251 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