New test for --disable-accelerated-2d-canvas.
New test for --disable-accelerated-2d-canvas.

Change the test which controls if chrome is passed the
--disable-accelerated-2d-canvas flag to use the new USE flag
accelerate_2d_canvas.

BUG=chromium-os:35448
TEST=build and install chromeos, run chrome and check chrome://gpu

Change-Id: Idc184e40dc88f940fd6c8d3b9b90a46999aed63f
Reviewed-on: https://gerrit.chromium.org/gerrit/35945
Reviewed-by: Jon Kliegman <7addd549d0b04b2dc663a0a7eb2c1810caf11d96@chromium.org>
Reviewed-by: Chris Masone <98e3d65c6b0e9e2391eb4c2e8b1e572b77e544ed@chromium.org>
Commit-Ready: Frank Henigman <4f3ccfa167f952ff7263448ff4377acff6a23e5c@chromium.org>
Tested-by: Frank Henigman <4f3ccfa167f952ff7263448ff4377acff6a23e5c@chromium.org>

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