cc: Add flag to use raster cheapness estimator

Add a command line flag to turn on the raster job cheapness estimator.
It will be used to schedule raster jobs according to their estimated
processing cost.

BUG=173426
TBR=piman

Review URL: https://chromiumcodereview.appspot.com/12185015

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@180399 0039d316-1c4b-4281-b951-d872f2087c98
6 files changed