Check buffer_pool_ for null in VideoCaptureController::PostStopping.

content/browser/renderer_host/media/video_capture_controller.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 "content/browser/renderer_host/media/video_capture_controller.h"
 
 #include <set>
 
 #include "base/bind.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 637 matching lines @@
 
 // This function is called when all buffers have been returned to controller,
 // or when device is stopped. It decides whether the device needs to be
 // restarted.
 void VideoCaptureController::PostStopping() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   DCHECK_EQ(state_, VIDEO_CAPTURE_STATE_STOPPING);
 
   // When clients still have some buffers, or device has not been stopped yet,
   // do nothing.
-  if (buffer_pool_->IsAnyBufferHeldForConsumers() || device_in_use_)
+  if ((buffer_pool_ && buffer_pool_->IsAnyBufferHeldForConsumers()) ||

[wjia(left Chromium), 2013/05/16 00:14:16]

Should this check be also added for other cases (whenever buffer_pool_ is used)?

[ncarter (slow), 2013/05/16 00:32:31]

It wouldn't hurt, but it's certainly not necessary everywhere. An example is
VideoCaptureController::ReturnBuffer, where if we've got a buffer to return,
then it seems reasonable to infer that we've received the buffer_pool_.

I admit that I don't fully understand the invariants of the various state
machine states in this code. I'll take a deeper look for other similar problems.

+      device_in_use_)
     return;
 
   {
     base::AutoLock lock(buffer_pool_lock_);
     buffer_pool_ = NULL;
   }
 
   // No more client. Therefore the controller is stopped.
   if (controller_clients_.empty() && pending_clients_.empty()) {
     state_ = VIDEO_CAPTURE_STATE_STOPPED;
@@ skipping 20 matching lines @@
     controller_clients_.push_back((*client_it));
     pending_clients_.erase(client_it++);
   }
   // Request the manager to start the actual capture.
   video_capture_manager_->Start(current_params_, this);
   state_ = VIDEO_CAPTURE_STATE_STARTED;
   device_in_use_ = true;
 }
 
 }  // namespace content