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

chrome/browser/search/iframe_source.h

Index: chrome/browser/search/iframe_source.h
diff --git a/chrome/browser/search/iframe_source.h b/chrome/browser/search/iframe_source.h
index c1a9348e7fa78babc2c3b1ef6eb9ba5b48ef5a41..80beefc298f1ef32c5b21fbefd3c11bf29faccf3 100644
--- a/chrome/browser/search/iframe_source.h
+++ b/chrome/browser/search/iframe_source.h
@@ -13,15 +13,13 @@
 class IframeSource : public content::URLDataSource {
  public:
   IframeSource();
-  virtual ~IframeSource();
+  ~IframeSource() override;
 
  protected:
   // Overridden from content::URLDataSource:
-  virtual std::string GetMimeType(
-      const std::string& path_and_query) const override;
-  virtual bool ShouldDenyXFrameOptions() const override;
-  virtual bool ShouldServiceRequest(
-      const net::URLRequest* request) const override;
+  std::string GetMimeType(const std::string& path_and_query) const override;
+  bool ShouldDenyXFrameOptions() const override;
+  bool ShouldServiceRequest(const net::URLRequest* request) const override;
 
   // Returns whether this source should serve data for a particular path.
   virtual bool ServesPath(const std::string& path) const = 0;