Cleanup: Update the path to geometry headers.

The geometry headers were moved from ui/gfx/ to ui/gfx/geometry, so we
are updating the include paths to fix this.

BUG=395370
TEST=None
R=tkent@chromium.org

Review URL: https://codereview.chromium.org/678593003

git-svn-id: svn://svn.chromium.org/blink/trunk@184418 bbb929c8-8fbe-4397-9dbb-9b2b20218538