Remove unnecessary includes to detangle these classes from other classes that have layering violations in preparation to move them to Source/platform

BUG=297477

Review URL: https://codereview.chromium.org/26432006

git-svn-id: svn://svn.chromium.org/blink/trunk@159154 bbb929c8-8fbe-4397-9dbb-9b2b20218538