Remove unused declaration.

Bug: none
Test: atest DisplayModeSwitchingTest
Change-Id: I8426d103ec6116a0a62b6e1e414a2e2dabf4f3c0
diff --git a/services/surfaceflinger/tests/unittests/SurfaceFlinger_DisplayModeSwitching.cpp b/services/surfaceflinger/tests/unittests/SurfaceFlinger_DisplayModeSwitching.cpp
index 32d57b5..5872a47 100644
--- a/services/surfaceflinger/tests/unittests/SurfaceFlinger_DisplayModeSwitching.cpp
+++ b/services/surfaceflinger/tests/unittests/SurfaceFlinger_DisplayModeSwitching.cpp
@@ -61,7 +61,6 @@
 
 protected:
     void setupScheduler(std::shared_ptr<scheduler::RefreshRateConfigs>);
-    void testChangeRefreshRate(bool isDisplayActive, bool isRefreshRequired);
 
     sp<DisplayDevice> mDisplay;
     mock::EventThread* mAppEventThread;