Bug 1054326: Initial attempt to submit Imagecompare test framework and test cases int...

...o the main branch
You need to at least document the values for frame as this is currently confusing. It looks like if it's 'root' nothing will happen, if it's 'chrome' it will switch to the system app at the end, and if it's anything else it will switch to the displayed app. Could you explain what your logic is doing? I suspect there's a simpler way.