Fix background tint for Button.Colored on API 22

Happens because we're using the compat drawable pre-v23, which means
that the compat tint is loaded into mInternalBackgroundTint, thus we
also need to handle any custom set tints.

Also improved the readability of BaseViewTest.

Test: included
BUG: 32368707

Change-Id: I30c77e0da617de4d6f160f4627de49157a6ea728
7 files changed