Standardize usage of virtual/override/final in extensions/

This patch was automatically generated by applying clang fixit hints
generated by the plugin to the source tree.

BUG=417463
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Review URL: https://codereview.chromium.org/664933004

Cr-Commit-Position: refs/heads/master@{#300475}
diff --git a/extensions/renderer/utils_native_handler.h b/extensions/renderer/utils_native_handler.h
index 1b2c8bb..407fb6a 100644
--- a/extensions/renderer/utils_native_handler.h
+++ b/extensions/renderer/utils_native_handler.h
@@ -13,7 +13,7 @@
 class UtilsNativeHandler : public ObjectBackedNativeHandler {
  public:
   explicit UtilsNativeHandler(ScriptContext* context);
-  virtual ~UtilsNativeHandler();
+  ~UtilsNativeHandler() override;
 
  private:
   // |args| consists of two arguments: a public class name, and a reference