Remove ContextClient from NavigatorBeacon

third_party/WebKit/Source/platform/Supplementable.h

Index: third_party/WebKit/Source/platform/Supplementable.h
diff --git a/third_party/WebKit/Source/platform/Supplementable.h b/third_party/WebKit/Source/platform/Supplementable.h
index c2b90df0f0a3ec2457dac03425f1d030a2dfbfe9..6ec435c81fc6819439cea6f3aaec688efd660573 100644
--- a/third_party/WebKit/Source/platform/Supplementable.h
+++ b/third_party/WebKit/Source/platform/Supplementable.h
@@ -98,7 +98,12 @@ class Supplement : public GarbageCollectedMixin {
   // 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,