[cast_channel] Make CastMessageHandler a CastSocket::Observer instead of CastTransport::Delegate

components/cast_channel/cast_socket_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 "components/cast_channel/cast_socket_service.h"
 
 #include "base/memory/ptr_util.h"
 #include "content/public/browser/browser_thread.h"
 
 using content::BrowserThread;
@@ skipping 34 matching lines @@
   return socket;
 }
 
 CastSocket* CastSocketService::GetSocket(int channel_id) const {
   DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
   DCHECK(channel_id > 0);
   const auto& socket_it = sockets_.find(channel_id);
   return socket_it == sockets_.end() ? nullptr : socket_it->second.get();
 }
 
+CastSocket::Observer* CastSocketService::GetObserver(const std::string& id) {
+  auto it = socket_observer_map_.find(id);
+  return it == socket_observer_map_.end() ? nullptr : it->second.get();
+}
+
+CastSocket::Observer* CastSocketService::AddObserver(
+    const std::string& id,
+    std::unique_ptr<CastSocket::Observer> observer) {
+  CastSocket::Observer* observer_ptr = observer.get();
+  socket_observer_map_.insert(std::make_pair(id, std::move(observer)));
+  return observer_ptr;
+}
+
 void CastSocketService::ShutdownOnUIThread() {}
 
 }  // namespace cast_channel