Remove universal inclusion rule for browser/extensions/

This rule prevents conditional source file exclusion to work
properly.

BUG=175798
BUG=234701
TEST=CQ

Review URL: https://codereview.chromium.org/14366039

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@195913 0039d316-1c4b-4281-b951-d872f2087c98
1 file changed