Previously introduced (Bug 28324) LayoutTests/fast/harness/use-page-cache.html verified that using overridePreference indeed enables page cache for a test.
As a follow up for the review comments in that bug, I've added a 'mirror' test that verifies that in the absence of override the page cache is disabled ('load' handler is called again when the window is navigated back to the same page).
Also, re-wrote test by moving all the JS into helper script so the use-page-cache.html can now be used as a simple template for page cache tests.
Created attachment 35173 [details]
Comment on attachment 35173 [details]
Removing r? because of Bugzilla memory loss - it was reviewed and discussed on IRC and agreed that it is not an optimal approach. I'll revisit this latter to see if it makes sense to have a 'template' for page cache tests.