Remove --enable-in-browser-thumbnailing, which is no longer necessary.
Remove --enable-in-browser-thumbnailing, which is no longer necessary.

BUG=chromium:120003
TEST=Manual

Change-Id: I7504cc165e617b09db8cf227e79711279ca6d108
Reviewed-on: https://gerrit.chromium.org/gerrit/24308
Tested-by: Yasuhiro Matsuda <9ec2621bb952ab212238ced42dcfb982244bde16@chromium.org>
Reviewed-by: Antoine Labour <9b5adc77717fb53f6e082b29cd49aa0d7f0ce7f0@chromium.org>
Commit-Ready: Yasuhiro Matsuda <9ec2621bb952ab212238ced42dcfb982244bde16@chromium.org>

chadversary/chromiumos.platform.login_manager,chadversary/chromiumos.platform.login_manager,chadversary/chromiumos.platform.login_manager