CC: Use format to calculate tile bytes.

If we don't we will use only 1/2 of our memory.

BUG=295185
NOTRY=true

Review URL: https://chromiumcodereview.appspot.com/24308002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@224750 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 224750