Style fixes in //ios

ios/web/public/web_state/web_state_user_data.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef IOS_WEB_PUBLIC_WEB_STATE_WEB_STATE_USER_DATA_H_
 #define IOS_WEB_PUBLIC_WEB_STATE_WEB_STATE_USER_DATA_H_
 
 #include "base/supports_user_data.h"
 #include "ios/web/public/web_state/web_state.h"
 
 namespace web {
 
 // A base class for classes attached to, and scoped to, the lifetime of a
 // WebState. For example:
 //
 // --- in foo.h ---
 // class Foo : public web::WebStateUserData<Foo> {
 //  public:
-//   virtual ~Foo();
+//   ~Foo() override;
 //   // ... more public stuff here ...
 //  private:
 //   explicit Foo(web::WebState* web_state);
 //   friend class web::WebStateUserData<Foo>;
 //   // ... more private stuff here ...
 // }
 // --- in foo.cc ---
 // DEFINE_WEB_CONTENTS_USER_DATA_KEY(Foo);
 //
 template <typename T>
 class WebStateUserData : public base::SupportsUserData::Data {
  public:
   // Creates an object of type T, and attaches it to the specified WebState.
   // If an instance is already attached, does nothing.
   static void CreateForWebState(WebState* web_state) {
     if (!FromWebState(web_state))
       web_state->SetUserData(UserDataKey(), new T(web_state));
   }
 
   // Retrieves the instance of type T that was attached to the specified
   // WebState (via CreateForWebState above) and returns it. If no instance
-  // of the type was attached, returns NULL.
+  // of the type was attached, returns null.
   static T* FromWebState(WebState* web_state) {
     return static_cast<T*>(web_state->GetUserData(UserDataKey()));
   }
   static const T* FromWebState(const WebState* web_state) {
     return static_cast<const T*>(web_state->GetUserData(UserDataKey()));
   }
   // Removes the instance attached to the specified WebState.
   static void RemoveFromWebState(WebState* web_state) {
     web_state->RemoveUserData(UserDataKey());
   }
@@ skipping 13 matching lines @@
 // a declaration. Without it, this would be merely a declaration of a template
 // specialization. (C++98: 14.7.3.15; C++11: 14.7.3.13)
 //
 #define DEFINE_WEB_STATE_USER_DATA_KEY(TYPE) \
   template <>                                \
   int web::WebStateUserData<TYPE>::kLocatorKey = 0
 
 }  // namespace web
 
 #endif  // IOS_WEB_PUBLIC_WEB_STATE_WEB_STATE_USER_DATA_H_