[Chromoting] A crash in DesktopSessionProxy::OnCaptureResult

remoting/host/desktop_session_proxy.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 "remoting/host/desktop_session_proxy.h"
 
 #include <stddef.h>
 
 #include <utility>
 
@@ skipping 466 matching lines @@
   shared_buffers_.erase(id);
 }
 
 void DesktopSessionProxy::OnCaptureResult(
     webrtc::DesktopCapturer::Result result,
     const SerializedDesktopFrame& serialized_frame) {
   DCHECK(caller_task_runner_->BelongsToCurrentThread());
 
   --pending_capture_frame_requests_;
 
+  if (!video_capturer_) {
+    return;
+  }
+
   if (result != webrtc::DesktopCapturer::Result::SUCCESS) {
     video_capturer_->OnCaptureResult(result, nullptr);
     return;
   }
 
   // Assume that |serialized_frame| is well-formed because it was received from
   // a more privileged process.
   scoped_refptr<IpcSharedBufferCore> shared_buffer_core =
       GetSharedBufferCore(serialized_frame.shared_buffer_id);
   CHECK(shared_buffer_core.get());
@@ skipping 49 matching lines @@
 }
 
 // static
 void DesktopSessionProxyTraits::Destruct(
     const DesktopSessionProxy* desktop_session_proxy) {
   desktop_session_proxy->caller_task_runner_->DeleteSoon(FROM_HERE,
                                                          desktop_session_proxy);
 }
 
 }  // namespace remoting