Stretch Allocation and Statistics view to occupy all awailable space

BUG=277984
R=alph@chromium.org

Review URL: https://codereview.chromium.org/200223006

git-svn-id: svn://svn.chromium.org/blink/trunk@169241 bbb929c8-8fbe-4397-9dbb-9b2b20218538