Revert of Remove a Platform::current() check from Mojo's error handler in WebSocket

third_party/WebKit/Source/modules/websockets/WebSocketHandleImpl.cpp

 // 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.
 
 #include "modules/websockets/WebSocketHandleImpl.h"
 
 #include "modules/websockets/WebSocketHandleClient.h"
 #include "platform/network/NetworkLog.h"
 #include "platform/network/WebSocketHandshakeRequest.h"
 #include "platform/network/WebSocketHandshakeResponse.h"
@@ skipping 106 matching lines @@
 }
 
 void WebSocketHandleImpl::disconnect()
 {
     m_websocket.reset();
     m_client = nullptr;
 }
 
 void WebSocketHandleImpl::onConnectionError()
 {
+    if (!blink::Platform::current()) {
+        // In the renderrer shutdown sequence, mojo channels are destructed and this
+        // function is called. On the other hand, blink objects became invalid
+        // *silently*, which means we must not touch |*client_| any more.
+        // TODO(yhirano): Remove this code once the shutdown sequence is fixed.
+        disconnect();
+        return;
+    }
+
     // Our connection to the WebSocket was dropped. This could be due to
     // exceeding the maximum number of concurrent websockets from this process.
 
     // TODO(darin): Communicate a more specific error here (see crbug/634502).
     OnFailChannel(
         "Error in connection establishment: net:"
         ":ERR_INSUFFICIENT_RESOURCES");
 }
 
 void WebSocketHandleImpl::OnFailChannel(const String& message)
@@ skipping 98 matching lines @@
 {
     NETWORK_DVLOG(1) << this << " OnClosingHandshake()";
     if (!m_client)
         return;
 
     m_client->didStartClosingHandshake(this);
     // |this| can be deleted here.
 }
 
 } // namespace blink