cc: Get rid of SurfaceDestroyed and use SurfaceDiscarded instead

cc/test/fake_surface_observer.h

Index: cc/test/fake_surface_observer.h
diff --git a/cc/test/fake_surface_observer.h b/cc/test/fake_surface_observer.h
index bf325e7d5b0892583740536a339bc1e86b087099..05125a6469306ad357b8034e64b1d36958bbb19a 100644
--- a/cc/test/fake_surface_observer.h
+++ b/cc/test/fake_surface_observer.h
@@ -39,7 +39,6 @@ class FakeSurfaceObserver : public SurfaceObserver {
                         bool* changed) override;
   void OnSurfaceCreated(const SurfaceInfo& surface_info) override;
   void OnSurfaceDiscarded(const SurfaceId& surface_id) override {}
-  void OnSurfaceDestroyed(const SurfaceId& surface_id) override {}
   void OnSurfaceDamageExpected(const SurfaceId& surface_id,
                                const BeginFrameArgs& args) override {}