Cast: make global_instance_ more strict

chrome/renderer/media/cast_ipc_dispatcher.cc

 // Copyright 2014 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/renderer/media/cast_ipc_dispatcher.h"
 
 #include "chrome/common/cast_messages.h"
 #include "chrome/renderer/media/cast_transport_sender_ipc.h"
 #include "ipc/ipc_message_macros.h"
 
 CastIPCDispatcher* CastIPCDispatcher::global_instance_ = NULL;
 
 CastIPCDispatcher::CastIPCDispatcher(
     const scoped_refptr<base::MessageLoopProxy>& io_message_loop)
     : channel_(NULL),
       io_message_loop_(io_message_loop) {
   DCHECK(io_message_loop_);
   DCHECK(!global_instance_);
 }
 
 CastIPCDispatcher::~CastIPCDispatcher() {
   DCHECK(io_message_loop_->BelongsToCurrentThread());
-  // Unfortunately, you do not always get a OnFilterRemoved call.
-  global_instance_ = NULL;
+  DCHECK(!global_instance_);
 }
 
 CastIPCDispatcher* CastIPCDispatcher::Get() {
   return global_instance_;
 }
 
 void CastIPCDispatcher::Send(IPC::Message* message) {
   DCHECK(io_message_loop_->BelongsToCurrentThread());
   if (channel_) {
     channel_->Send(message);
@@ skipping 32 matching lines @@
 void CastIPCDispatcher::OnFilterRemoved() {
   DCHECK(io_message_loop_->BelongsToCurrentThread());
   DCHECK_EQ(this, global_instance_);
   global_instance_ = NULL;
   channel_ = NULL;
 }
 
 void CastIPCDispatcher::OnChannelClosing() {
   DCHECK(io_message_loop_->BelongsToCurrentThread());
   DCHECK_EQ(this, global_instance_);
-  channel_ = NULL;
 }
 
 void CastIPCDispatcher::OnReceivedPacket(
     int32 channel_id,
     const media::cast::transport::Packet& packet) {
   CastTransportSenderIPC* sender = id_map_.Lookup(channel_id);
   if (sender) {
     sender->OnReceivedPacket(packet);
   } else {
     LOG(ERROR) << "CastIPCDispatcher::OnReceivedPacket "
@@ skipping 20 matching lines @@
     base::TimeTicks time_sent,
     uint32 rtp_timestamp) {
   CastTransportSenderIPC* sender = id_map_.Lookup(channel_id);
   if (sender) {
     sender->OnRtpStatistics(audio, sender_info, time_sent, rtp_timestamp);
   } else {
     LOG(ERROR)
         << "CastIPCDispatcher::OnNotifystatusChange on non-existing channel.";
   }
 }