Standardize usage of virtual/override/final in chrome/browser/extensions/

chrome/browser/extensions/api/system_private/system_private_api.h

Index: chrome/browser/extensions/api/system_private/system_private_api.h
diff --git a/chrome/browser/extensions/api/system_private/system_private_api.h b/chrome/browser/extensions/api/system_private/system_private_api.h
index bebd362f774e94dda35ef2c84309d3de9701d3f9..30d230691259030bb595c55e77c1473331e27daf 100644
--- a/chrome/browser/extensions/api/system_private/system_private_api.h
+++ b/chrome/browser/extensions/api/system_private/system_private_api.h
@@ -19,10 +19,10 @@ class SystemPrivateGetIncognitoModeAvailabilityFunction
                              SYSTEMPRIVATE_GETINCOGNITOMODEAVAILABILITY)
 
  protected:
-  virtual ~SystemPrivateGetIncognitoModeAvailabilityFunction() {}
+  ~SystemPrivateGetIncognitoModeAvailabilityFunction() override {}
 
   // ExtensionFunction:
-  virtual bool RunSync() override;
+  bool RunSync() override;
 };
 
 // API function which returns the status of system update.
@@ -33,10 +33,10 @@ class SystemPrivateGetUpdateStatusFunction
                              SYSTEMPRIVATE_GETUPDATESTATUS)
 
  protected:
-  virtual ~SystemPrivateGetUpdateStatusFunction() {}
+  ~SystemPrivateGetUpdateStatusFunction() override {}
 
   // ExtensionFunction:
-  virtual bool RunSync() override;
+  bool RunSync() override;
 };
 
 // API function which returns the Google API key.
@@ -45,10 +45,10 @@ class SystemPrivateGetApiKeyFunction : public SyncExtensionFunction {
   DECLARE_EXTENSION_FUNCTION("systemPrivate.getApiKey", SYSTEMPRIVATE_GETAPIKEY)
 
  protected:
-  virtual ~SystemPrivateGetApiKeyFunction() {}
+  ~SystemPrivateGetApiKeyFunction() override {}
 
   // ExtensionFunction:
-  virtual bool RunSync() override;
+  bool RunSync() override;
 };
 
 // Dispatches systemPrivate.onBrightnessChanged event for extensions.