Add/Remove static to functions. Name change. Change-Id: I5de3efc23cd151fe8e70fe67a7a11acfcfa707dc
As we add more tests to datarate_test.cc, it's growing bigger and hard to find specific test. Split it to vp8, vp9 and svc ones. Change-Id: Ie8c302010cf304a95554bee19d87ddc90498d0fb