Clarify ownership of GpuVideoDecodeAcceleratorHost and avoid crash on context loss.

content/common/gpu/client/gpu_video_decode_accelerator_host.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/common/gpu/client/gpu_video_decode_accelerator_host.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
 #include "content/common/gpu/client/gpu_channel_host.h"
@@ skipping 101 matching lines @@
   Send(new AcceleratedVideoDecoderMsg_Flush(decoder_route_id_));
 }
 
 void GpuVideoDecodeAcceleratorHost::Reset() {
   DCHECK(CalledOnValidThread());
   Send(new AcceleratedVideoDecoderMsg_Reset(decoder_route_id_));
 }
 
 void GpuVideoDecodeAcceleratorHost::Destroy() {
   DCHECK(CalledOnValidThread());
-  channel_->RemoveRoute(decoder_route_id_);
+  if (channel_)
+    channel_->RemoveRoute(decoder_route_id_);
   client_ = NULL;
   Send(new AcceleratedVideoDecoderMsg_Destroy(decoder_route_id_));
   delete this;
 }
 
-GpuVideoDecodeAcceleratorHost::~GpuVideoDecodeAcceleratorHost() {}
+GpuVideoDecodeAcceleratorHost::~GpuVideoDecodeAcceleratorHost() {
+  DCHECK(CalledOnValidThread());
+  DCHECK(!client_) << "destructor called without Destroy being called!";
+}
 
 void GpuVideoDecodeAcceleratorHost::Send(IPC::Message* message) {
   // After OnChannelError is called, the client should no longer send
   // messages to the gpu channel through this object.  But queued posted tasks
   // can still be draining, so we're forgiving and simply ignore them.
   bool error = false;
   uint32 message_type = message->type();
   if (!channel_) {
     delete message;
     DLOG(ERROR) << "Send(" << message_type << ") after error ignored";
@@ skipping 53 matching lines @@
 }
 
 void GpuVideoDecodeAcceleratorHost::OnErrorNotification(uint32 error) {
   DCHECK(CalledOnValidThread());
   if (!client_)
     return;
   client_->NotifyError(
       static_cast<media::VideoDecodeAccelerator::Error>(error));
   client_ = NULL;
 }