SF: Creating a basic Scheduler class.

Added a flag that can be turned on at runtime, and turns on the new path.
Added a basic Scheduler that encapsulates SF and App thread.

This is part of the go/surfce-flinger-scheduler move.

Test: All SF tests pass. Adding a Scheduler test in the next CL.

Change-Id: Ic45b662f82d60da1172bf64485c838344082b306
diff --git a/services/surfaceflinger/Android.bp b/services/surfaceflinger/Android.bp
index 05535a5..da57511 100644
--- a/services/surfaceflinger/Android.bp
+++ b/services/surfaceflinger/Android.bp
@@ -125,6 +125,7 @@
         "Scheduler/EventControlThread.cpp",
         "Scheduler/EventThread.cpp",
         "Scheduler/MessageQueue.cpp",
+        "Scheduler/Scheduler.cpp",
         "StartPropertySetThread.cpp",
         "SurfaceFlinger.cpp",
         "SurfaceInterceptor.cpp",