Bug: 326982 Editable fields in the Metrics pane should use the correct mouse cursor

BUG=326982
R=pfeldman@chromium.org

Review URL: https://codereview.chromium.org/109203004

git-svn-id: svn://svn.chromium.org/blink/trunk@163439 bbb929c8-8fbe-4397-9dbb-9b2b20218538