Remove ContextClient from NavigatorBeacon

third_party/WebKit/Source/platform/Supplementable.h

 /*
  * Copyright (C) 2012 Google, Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 80 matching lines @@
 
 template <typename T>
 class Supplementable;
 
 template <typename T>
 class Supplement : public GarbageCollectedMixin {
  public:
   // TODO(haraken): Remove the default constructor.
   // All Supplement objects should be instantiated with m_host.
   Supplement() {}
+
   explicit Supplement(T& host) : m_host(&host) {}
+
+  // Supplementable and its supplements live and die together.
+  // Thus host() should never return null (if the default constructor
+  // is completely removed).
   T* host() const { return m_host; }
 
   static void provideTo(Supplementable<T>& host,
                         const char* key,
                         Supplement<T>* supplement) {
     host.provideSupplement(key, supplement);
   }
 
   static Supplement<T>* from(Supplementable<T>& host, const char* key) {
     return host.requireSupplement(key);
@@ skipping 71 matching lines @@
 };
 
 template <typename T>
 struct ThreadingTrait<Supplementable<T>> {
   static const ThreadAffinity Affinity = ThreadingTrait<T>::Affinity;
 };
 
 }  // namespace blink
 
 #endif  // Supplementable_h