GitLab

GTK message-pump defines its own observer, but it has the same name as the
message-pump observers used in other platforms. So rename the GTK version
to MessagePumpGdkObserver.

Also, GTK version of message-pump dispatcher is never used, so get rid of
that.

BUG=145600
R=piman@chromium.org, thakis@chromium.org

Review URL: https://codereview.chromium.org/23537016

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@221846 0039d316-1c4b-4281-b951-d872f2087c98