[cast_channel] Make CastSocket not inherit from ApiResource

extensions/browser/api/cast_channel/cast_channel_service.cc

+// Copyright 2017 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 "extensions/browser/api/cast_channel/cast_channel_service.h"
+
+#include "base/memory/ptr_util.h"
+
+namespace extensions {
+namespace api {
+namespace cast_channel {
+
+CastSocketData::CastSocketData() = default;
+
+CastSocketData::~CastSocketData() {
+  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+}
+
+int CastSocketData::AddSocket(CastSocket* socket) {
+  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+  DCHECK(socket);
+  int id = sockets_.size() + 1;

[mark a. foltz, 2017/05/18 18:02:26]

This will assign duplicate ids as the size of sockets_ changes.

[zhaobin, 2017/05/24 01:51:39]

Done.

+  sockets_.insert(std::make_pair(id, base::WrapUnique(socket)));
+  socket->set_id(id);
+  return id;
+}
+
+void CastSocketData::RemoveSocket(int channel_id) {
+  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);

[mark a. foltz, 2017/05/18 18:02:26]

DCHECK(channel_id > 0)

[zhaobin, 2017/05/24 01:51:39]

Done.

+  sockets_.erase(channel_id);
+}
+
+CastSocket* CastSocketData::GetSocket(int channel_id) const {
+  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);

[mark a. foltz, 2017/05/18 19:12:04]

DCHECK(channel_id > 0)

[zhaobin, 2017/05/24 01:51:39]

Done.

+  const auto& socket_it = sockets_.find(channel_id);
+  return socket_it == sockets_.end() ? nullptr : socket_it->second.get();
+}
+
+CastChannelService::CastChannelService() = default;
+CastChannelService::~CastChannelService() = default;
+
+CastSocketData* CastChannelService::GetOrCreateSocketData() {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::IO);

[mark a. foltz, 2017/05/18 18:02:26]

Since sockets_ is created on the IO thread it follows that this API must also be
called on the IO thread, so you could DCHECK_CURRENTLY_ON throughout.  However
thread_checker_ is more friendly for unit testing IIUC.

[zhaobin, 2017/05/24 01:51:39]

Seems unable to use |thread_checker_| here. CastChannelService is
created/destroyed on the UI thread, but this API must be called on the IO
thread.

[mark a. foltz, 2017/05/24 17:44:10]

This should be called out in the comments.

[zhaobin, 2017/05/24 18:12:57]

Done.

+  if (!sockets_)
+    sockets_.reset(new CastSocketData());
+  return sockets_.get();
+}
+
+}  // namespace cast_channel
+}  // namespace api
+}  // namespace extensions