Remove GPU_FEATURE_TYPE_3D_CSS and --disable-accelerated-layers
We ignore GPU_FEATURE_TYPE_3D_CSS, so remove it.
Nothing sets --disable-accelerated-layers, and it doesn't correspond to
a production path, so remove it.
This lets us clean up some WebPreferences fields which are always set to
true.
Also remove WebPreferences::accelerated_compositing_for_plugins_enabled
which is always true.
BUG=362164,365847
R=bbudge@chromium.org, danakj@chromium.org, tsepez@chromium.org
Review URL: https://codereview.chromium.org/
239973005
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@266226 0039d316-1c4b-4281-b951-d872f2087c98