debugger: Only show upload if no SKP has been uploaded yet.
debugger: Only show upload if no SKP has been uploaded yet.

Also hide the controls if an SKP has been updated.

Screenshots:
   https://screenshot.googleplex.com/5TMXZpCx2r5.png
   https://screenshot.googleplex.com/Yf1ZZ0rn7hh.png

BUG=skia:
R=rmistry

Review-Url: https://codereview.chromium.org/2118733004

google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot