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

chrome/browser/extensions/startup_helper.cc

Index: chrome/browser/extensions/startup_helper.cc
diff --git a/chrome/browser/extensions/startup_helper.cc b/chrome/browser/extensions/startup_helper.cc
index e9b33cbf646cc9cf07d53b49cce50ec197f8ecf1..b90fed3cd9b87896a376fea0c4f63ce76ab8a954 100644
--- a/chrome/browser/extensions/startup_helper.cc
+++ b/chrome/browser/extensions/startup_helper.cc
@@ -138,13 +138,13 @@ class ValidateCrxHelper : public SandboxedUnpackerClient {
   }
 
  protected:
-  virtual ~ValidateCrxHelper() {}
+  ~ValidateCrxHelper() override {}
 
-  virtual void OnUnpackSuccess(const base::FilePath& temp_dir,
-                               const base::FilePath& extension_root,
-                               const base::DictionaryValue* original_manifest,
-                               const Extension* extension,
-                               const SkBitmap& install_icon) override {
+  void OnUnpackSuccess(const base::FilePath& temp_dir,
+                       const base::FilePath& extension_root,
+                       const base::DictionaryValue* original_manifest,
+                       const Extension* extension,
+                       const SkBitmap& install_icon) override {
     finished_ = true;
     success_ = true;
     BrowserThread::PostTask(BrowserThread::UI,
@@ -153,7 +153,7 @@ class ValidateCrxHelper : public SandboxedUnpackerClient {
                                        this));
   }
 
-  virtual void OnUnpackFailure(const base::string16& error) override {
+  void OnUnpackFailure(const base::string16& error) override {
     finished_ = true;
     success_ = false;
     error_ = error;