Add resizing buttons for the command panel.
Add resizing buttons for the command panel.

Also moved the GPU toggle and "Display Batch Bounds" checkbox to the right hand panel.

Screenshot:
  https://screenshot.googleplex.com/DAGVAfhfivH.png

BUG=skia:
R=rmistry

Review-Url: https://codereview.chromium.org/2113723004

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