SurfaceFlinger: override frame rate for applications that use setFrameRate

When possible, override the frame rate of an app if it explicitly
set a preferred frame rate.

Test: atest FrameRateOverrideHostTest
Test: SF unit tests
Bug: 170502573
Change-Id: Ifcb7dd1ad0423b05efe8a0e86f2d988c49e74054
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index 96d0499..c4c4813 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -639,6 +639,8 @@
     void repaintEverythingForHWC() override;
     // Called when kernel idle timer has expired. Used to update the refresh rate overlay.
     void kernelTimerChanged(bool expired) override;
+    // Called when the frame rate override list changed to trigger an event.
+    void triggerOnFrameRateOverridesChanged() override;
     // Toggles the kernel idle timer on or off depending the policy decisions around refresh rates.
     void toggleKernelIdleTimer();
     // Keeps track of whether the kernel idle timer is currently enabled, so we don't have to