Add screensaver flag use to chromeos-init.
Add screensaver flag use to chromeos-init.

Change-Id: I7bbcd86c4860f21dcee66821456266678715e477

BUG=chromium-os:9869
TEST=Built image with x86-generic. Verified screensaver showed when I pressed
the power button

Review URL: http://codereview.chromium.org/5558001

joshfire/chromiumos-platform-login_manager,joshfire/chromiumos-platform-login_manager,chadversary/chromiumos.platform.login_manager,chadversary/chromiumos.platform.login_manager,chadversary/chromiumos.platform.login_manager,joshfire/chromiumos-platform-login_manager