Standardize usage of virtual/override/final in extensions/

extensions/browser/api/system_display/system_display_api.h

Index: extensions/browser/api/system_display/system_display_api.h
diff --git a/extensions/browser/api/system_display/system_display_api.h b/extensions/browser/api/system_display/system_display_api.h
index f447d9b2ab23cada48adeac1f2479a569c839f0e..559643f5259be652dbb5a0ce7036ee98d7d3958b 100644
--- a/extensions/browser/api/system_display/system_display_api.h
+++ b/extensions/browser/api/system_display/system_display_api.h
@@ -16,8 +16,8 @@ class SystemDisplayGetInfoFunction : public SyncExtensionFunction {
   DECLARE_EXTENSION_FUNCTION("system.display.getInfo", SYSTEM_DISPLAY_GETINFO);
 
  protected:
-  virtual ~SystemDisplayGetInfoFunction() {}
-  virtual bool RunSync() override;
+  ~SystemDisplayGetInfoFunction() override {}
+  bool RunSync() override;
 };
 
 class SystemDisplaySetDisplayPropertiesFunction : public SyncExtensionFunction {
@@ -26,8 +26,8 @@ class SystemDisplaySetDisplayPropertiesFunction : public SyncExtensionFunction {
                              SYSTEM_DISPLAY_SETDISPLAYPROPERTIES);
 
  protected:
-  virtual ~SystemDisplaySetDisplayPropertiesFunction() {}
-  virtual bool RunSync() override;
+  ~SystemDisplaySetDisplayPropertiesFunction() override {}
+  bool RunSync() override;
 };
 
 }  // namespace extensions