add --sync to adb push in bin/droid

This skips pushing files that are already present.

Change-Id: Ibe86be1e553da3cbe9d02d00764164d9e0745f8d
Reviewed-on: https://skia-review.googlesource.com/138164
Commit-Queue: Mike Klein <mtklein@chromium.org>
Commit-Queue: Hal Canary <halcanary@google.com>
Auto-Submit: Mike Klein <mtklein@chromium.org>
Reviewed-by: Hal Canary <halcanary@google.com>
1 file changed