Renamed the fuction from "test_image" to "test_image_content";
renamed the source file to match.
BUG=None
TEST=build both x86 and arm images
Change-Id: I158f2c5bc0f2fc260d48bd125a1899e6a21d7b79
Reviewed-on: http://gerrit.chromium.org/gerrit/5821
Reviewed-by: Vince Laviano <vlaviano@chromium.org>
Tested-by: Richard Barnette <jrbarnette@chromium.org>