Prefer ContextClient mixin over manual ExecutionContext handling.

third_party/WebKit/Source/modules/presentation/PresentationConnectionList.cpp

 // Copyright 2016 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.
 
 #include "modules/presentation/PresentationConnectionList.h"
 
 #include "core/frame/UseCounter.h"
 #include "modules/EventTargetModules.h"
 #include "modules/presentation/PresentationConnection.h"
 #include "modules/presentation/PresentationConnectionAvailableEvent.h"
 
 namespace blink {
 
 PresentationConnectionList::PresentationConnectionList(
     ExecutionContext* context)
-    : m_executionContext(context) {}
+    : ContextClient(context) {}
 
 const AtomicString& PresentationConnectionList::interfaceName() const {
   return EventTargetNames::PresentationConnectionList;
 }
 
 const HeapVector<Member<PresentationConnection>>&
 PresentationConnectionList::connections() const {
   return m_connections;
 }
 
@@ skipping 17 matching lines @@
   dispatchEvent(PresentationConnectionAvailableEvent::create(
       EventTypeNames::connectionavailable, connection));
 }
 
 bool PresentationConnectionList::isEmpty() {
   return m_connections.isEmpty();
 }
 
 DEFINE_TRACE(PresentationConnectionList) {
   visitor->trace(m_connections);
-  visitor->trace(m_executionContext);
   EventTargetWithInlineData::trace(visitor);
+  ContextClient::trace(visitor);
 }
 
 }  // namespace blink