Hide spelling service feedback behind a flag and a field trial
This CL hides spelling service feedback behind a command-line flag
--enable-spelling-service-feedback, so that users can choose whether to send
feedback. The flag can also be flipped from chrome://flags. Even with the flag
enabled, only field-trial participants will be sending feedback.
BUG=170514,247444
Review URL: https://chromiumcodereview.appspot.com/
16206020
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@205042 0039d316-1c4b-4281-b951-d872f2087c98