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

chrome/browser/browsing_data/browsing_data_channel_id_helper.cc

Index: chrome/browser/browsing_data/browsing_data_channel_id_helper.cc
diff --git a/chrome/browser/browsing_data/browsing_data_channel_id_helper.cc b/chrome/browser/browsing_data/browsing_data_channel_id_helper.cc
index 2c83443a59067c389e19cd235ccdf902c17886ed..bf495b75336fbe86451ce09ab6854f282fce4497 100644
--- a/chrome/browser/browsing_data/browsing_data_channel_id_helper.cc
+++ b/chrome/browser/browsing_data/browsing_data_channel_id_helper.cc
@@ -24,11 +24,11 @@ class BrowsingDataChannelIDHelperImpl
       net::URLRequestContextGetter* request_context);
 
   // BrowsingDataChannelIDHelper methods.
-  virtual void StartFetching(const FetchResultCallback& callback) override;
-  virtual void DeleteChannelID(const std::string& server_id) override;
+  void StartFetching(const FetchResultCallback& callback) override;
+  void DeleteChannelID(const std::string& server_id) override;
 
  private:
-  virtual ~BrowsingDataChannelIDHelperImpl();
+  ~BrowsingDataChannelIDHelperImpl() override;
 
   // Fetch the certs. This must be called in the IO thread.
   void FetchOnIOThread();