Add plumbing for upcoming setFrameRate() api

Add plumbing from the app to surface flinger for the
ANativeWindow_setFrameRate() and ASurfaceTransaction_setFrameRate() api
calls we'll be adding soon.

We don't do anything in surface flinger with this data yet.

Bug: 143912624

Test: Added a new test, SetFrameRateTest.
Change-Id: I1cab87f3ce5afca4591a39d8e7a42cb1e86a368f
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index e90cf41..4f042db 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -3480,6 +3480,9 @@
             flags |= eTraversalNeeded;
         }
     }
+    if (what & layer_state_t::eFrameRateChanged) {
+        if (layer->setFrameRate(s.frameRate)) flags |= eTraversalNeeded;
+    }
     // This has to happen after we reparent children because when we reparent to null we remove
     // child layers from current state and remove its relative z. If the children are reparented in
     // the same transaction, then we have to make sure we reparent the children first so we do not