Add refresh rate stats to TimeStats.

Bug: 122905821
Test: libsurfaceflinger_test
Test: dumpsys SurfaceFlinger --timestats -dump --proto
Change-Id: I99b38497f054f86bebba0813134f1c1eaf632b47
diff --git a/services/surfaceflinger/tests/unittests/Android.bp b/services/surfaceflinger/tests/unittests/Android.bp
index b2bcb45..b1d45f39 100644
--- a/services/surfaceflinger/tests/unittests/Android.bp
+++ b/services/surfaceflinger/tests/unittests/Android.bp
@@ -58,6 +58,7 @@
         "mock/MockMessageQueue.cpp",
         "mock/MockNativeWindowSurface.cpp",
         "mock/MockSurfaceInterceptor.cpp",
+        "mock/MockTimeStats.cpp",
         "mock/system/window/MockNativeWindow.cpp",
     ],
     static_libs: [