GitLab

Allow users to clear all the log messages in about://instant which makes
debugging a lot easier. Remove the old "Reset" button since it becomes
confusing which one does what (and that button isn't really that useful
anyway).

TESTED=navigate to about://instant, click "Clear"
BUG=none


Review URL: https://chromiumcodereview.appspot.com/12377095

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@186270 0039d316-1c4b-4281-b951-d872f2087c98