Revert "Revert "Revert "SF: Remove refresh_rate_switching flag."""

This reverts commit aa52b007cb5c96d6124a293ca80c430c7051f7f3.

Reason for revert: The original revert cause a failure: b/148821456. So the revert was created. Which caused a build failure b/148835312. Reverting the original change and fixing the test (that caused build failure) with it.

Bug: 148835312
Bug: 148821456
Bug: 148835894
Test: build, install on coral.
Test: adb shell /data/nativetest64/libsurfaceflinger_unittest/libsurfaceflinger_unittest
Change-Id: I48964c7c27ef53e8fb03d959ef85ee2ec64e1ed1
diff --git a/services/surfaceflinger/sysprop/SurfaceFlingerProperties.sysprop b/services/surfaceflinger/sysprop/SurfaceFlingerProperties.sysprop
index 0653959..ed2b220 100644
--- a/services/surfaceflinger/sysprop/SurfaceFlingerProperties.sysprop
+++ b/services/surfaceflinger/sysprop/SurfaceFlingerProperties.sysprop
@@ -301,6 +301,18 @@
     prop_name: "ro.surface_flinger.display_primary_white"
 }
 
+# refreshRateSwitching indicates whether SurfaceFlinger should use refresh rate
+# switching on the device, e.g. to switch between 60 and 90 Hz. The settings
+# below that are related to refresh rate switching will only have an effect if
+# refresh_rate_switching is enabled.
+prop {
+    api_name: "refresh_rate_switching"
+    type: Boolean
+    scope: System
+    access: Readonly
+    prop_name: "ro.surface_flinger.refresh_rate_switching"
+}
+
 prop {
     api_name: "set_idle_timer_ms"
     type: Integer