Update {virtual,override} to follow C++11 style in components.

components/webdata/common/web_data_results.h

Index: components/webdata/common/web_data_results.h
diff --git a/components/webdata/common/web_data_results.h b/components/webdata/common/web_data_results.h
index 6353db177a0823d42ff50463089fb0cb6e488c85..d6d07fd07c9a008e15fc66c4ffb748816df48e1f 100644
--- a/components/webdata/common/web_data_results.h
+++ b/components/webdata/common/web_data_results.h
@@ -67,7 +67,7 @@ template <class T> class WDResult : public WDTypedResult {
       : WDTypedResult(type), value_(v) {
   }
 
-  virtual ~WDResult() {
+  ~WDResult() override {
   }
 
   // Return a single value result.
@@ -91,11 +91,10 @@ template <class T> class WDDestroyableResult : public WDResult<T> {
         callback_(callback) {
   }
 
-  virtual ~WDDestroyableResult() {
+  ~WDDestroyableResult() override {
   }
 
-
-  virtual void Destroy()  override {
+  void Destroy() override {
     if (!callback_.is_null()) {
       callback_.Run(this);
     }