Fix Native Messaging to handle missing caller RenderWidgetHost.

chrome/browser/extensions/api/messaging/message_service.cc

 // Copyright (c) 2012 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 "chrome/browser/extensions/api/messaging/message_service.h"
 
 #include "base/atomic_sequence_num.h"
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/json/json_writer.h"
@@ skipping 385 matching lines @@
   if (policy_permission == DISALLOW) {
     DispatchOnDisconnect(source, receiver_port_id, kProhibitedByPoliciesError);
     return;
   }
 
   scoped_ptr<MessageChannel> channel(new MessageChannel());
   channel->opener.reset(new ExtensionMessagePort(source, MSG_ROUTING_CONTROL,
                                                  source_extension_id));
 
   // Get handle of the native view and pass it to the native messaging host.
+  content::RenderWidgetHost* render_widget_host =
+      content::RenderWidgetHost::FromID(source_process_id, source_routing_id);
   gfx::NativeView native_view =
-      content::RenderWidgetHost::FromID(source_process_id, source_routing_id)->
-          GetView()->GetNativeView();
+      render_widget_host ? render_widget_host->GetView()->GetNativeView()
+                         : nullptr;
 
   std::string error = kReceivingEndDoesntExistError;
   scoped_ptr<NativeMessageHost> native_host = NativeMessageHost::Create(
       native_view,
       source_extension_id,
       native_app_name,
       policy_permission == ALLOW_ALL,
       &error);
 
   // Abandon the channel.
   if (!native_host.get()) {
     LOG(ERROR) << "Failed to create native process.";
-    DispatchOnDisconnect(
-        source, receiver_port_id, error);
+    DispatchOnDisconnect(source, receiver_port_id, error);
     return;
   }
   channel->receiver.reset(new NativeMessagePort(
       weak_factory_.GetWeakPtr(), receiver_port_id, native_host.Pass()));
 
   // Keep the opener alive until the channel is closed.
   channel->opener->IncrementLazyKeepaliveCount();
 
   AddChannel(channel.release(), receiver_port_id);
 #else  // !(defined(OS_WIN) || defined(OS_MACOSX) || defined(OS_LINUX))
@@ skipping 433 matching lines @@
                                              int channel_id) {
   MessageChannelMap::iterator channel_iter = channels_.find(channel_id);
   if (channel_iter != channels_.end()) {
     for (const PendingMessage& message : queue) {
       DispatchMessage(message.first, channel_iter->second, message.second);
     }
   }
 }
 
 }  // namespace extensions