Merge changes Icf7cf2fd,I325521b7,Ia80c865d,I73599f62,I8526e671, ... into pi-dev

* changes:
  SF: Use display device factory in unit test
  SF: Introduce mock::NativeWindowSurface
  SF: Refactor display device creation
  SF: Introduce mock::NativeWindow
  SF: Introduce mock::DisplaySurface
  SF: Introduce mock::EventControlThread
  SF: Separate EventControlThread into interface and impl
  SF: Define mock::SurfaceInterceptor
  SF: Separate SurfaceInterceptor into interface and impl
  SF: Define mock::MessageQueue
  SF: Separate MessageQueue into interface and impl
  SF: libsurfaceflinger_unittest should skip SF ctor
  SF: Switch to internal display setup