SF: dispatch add testing surface for VSyncDispatch

Adds a stubbable/mockable surface to the VSyncDispatch class so that
an test relying on this object can be built.

Bug: 140303479
Test: libsurfaceflinger_unittest --gtest_filter="VSyncDisp*"

Change-Id: I7e0a6b14e7032c89c32595a624eef4f75e1ea1ad
diff --git a/services/surfaceflinger/tests/unittests/Android.bp b/services/surfaceflinger/tests/unittests/Android.bp
index 246a62f..78114a1 100644
--- a/services/surfaceflinger/tests/unittests/Android.bp
+++ b/services/surfaceflinger/tests/unittests/Android.bp
@@ -54,7 +54,7 @@
         "FrameTracerTest.cpp",
         "TransactionApplicationTest.cpp",
         "StrongTypingTest.cpp",
-        "VSyncDispatchTest.cpp",
+        "VSyncDispatchTimerQueueTest.cpp",
         "mock/DisplayHardware/MockComposer.cpp",
         "mock/DisplayHardware/MockDisplay.cpp",
         "mock/DisplayHardware/MockPowerAdvisor.cpp",