Broadcast Channel: Avoid poking at the heap after Blink shutdown

third_party/WebKit/Source/modules/broadcastchannel/BroadcastChannel.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/broadcastchannel/BroadcastChannel.h"
 
 #include "bindings/core/v8/SerializedScriptValue.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/events/EventQueue.h"
 #include "core/events/MessageEvent.h"
@@ skipping 56 matching lines @@
     return;
 
   Vector<char> data;
   value->toWireBytes(data);
   Vector<uint8_t> mojoData;
   mojoData.appendVector(data);
   m_remoteClient->OnMessage(std::move(mojoData));
 }
 
 void BroadcastChannel::close() {
+  if (!Platform::current()) {
+    // TODO(rockot): Remove this hack once renderer shutdown sequence is fixed.
+    // Note that reaching this code indicates that the MessageLoop has already
+    // been torn down, so it's impossible for further incoming messages to be
+    // dispatched on |m_binding| or reply callbacks to be invoked from
+    // |m_remoteClient|.
+    return;
+  }
   m_remoteClient.reset();
   if (m_binding.is_bound())
     m_binding.Close();
 }
 
 const AtomicString& BroadcastChannel::interfaceName() const {
   return EventTargetNames::BroadcastChannel;
 }
 
 bool BroadcastChannel::hasPendingActivity() const {
@@ skipping 55 matching lines @@
       &remoteCientRequest);
   m_remoteClient.Bind(std::move(remoteClientInfo));
   m_remoteClient.set_connection_error_handler(convertToBaseCallback(
       WTF::bind(&BroadcastChannel::onError, wrapWeakPersistent(this))));
 
   provider->ConnectToChannel(m_origin, m_name, std::move(localClientInfo),
                              std::move(remoteCientRequest));
 }
 
 }  // namespace blink