[clang] Fix more clang plugin warnings in gmock objects

Discovered by passing "check-gmock-objects" to find-bad-plugins and fixing the fallout.

Bug: 589969
Change-Id: Ib71a23035870b3d535683ce0f93182b3446956e6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3851441
Reviewed-by: Nico Weber <[email protected]>
Owners-Override: Nico Weber <[email protected]>
Commit-Queue: Arthur Eubanks <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1038843}
diff --git a/components/exo/surface_test_util.h b/components/exo/surface_test_util.h
index 876709c..a86d348 100644
--- a/components/exo/surface_test_util.h
+++ b/components/exo/surface_test_util.h
@@ -15,7 +15,7 @@
   SurfaceObserverForTest();
   SurfaceObserverForTest(const SurfaceObserverForTest&) = delete;
   SurfaceObserverForTest& operator=(const SurfaceObserverForTest&) = delete;
-  virtual ~SurfaceObserverForTest();
+  ~SurfaceObserverForTest() override;
 
   // SurfaceObserver overrides
   void OnSurfaceDestroying(Surface* surface) override {}