Make 'License' field in third-party metadata required

This will simplify the addition of a tool to check licenses for the purpose of
the Android WebView build.

See also http://codereview.chromium.org/10827099

Also adds other missing fields to these README.chromium files as required by
presubmit checks and fixes a regex used to enforce this.

BUG=138921

Review URL: https://chromiumcodereview.appspot.com/10821103

git-svn-id: http://src.chromium.org/svn/trunk/src/third_party/gles2_book@149423 4ff67af0-8c30-449e-8e8b-ad334ec8d88c
1 file changed