[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 = std::find_if(
+      socket_observer_map_.begin(), socket_observer_map_.end(),
+      [id](const std::pair<const std::string,

[mark a. foltz, 2017/06/20 01:16:43]

Can the parameter passed to the lambda be const auto ?

[zhaobin, 2017/06/20 17:50:05]

Seems not.. Got ''auto' not allowed in lambda parameter' compile error.

+                           std::unique_ptr<CastSocket::Observer>>& entry) {
+        return entry.first == id;
+      });
+  return it == socket_observer_map_.end() ? nullptr : it->second.get();
+}
+
+void CastSocketService::AddObserver(
+    const std::string& id,
+    std::unique_ptr<CastSocket::Observer> observer) {
+  socket_observer_map_.insert(std::make_pair(id, std::move(observer)));
+}
+
 void CastSocketService::ShutdownOnUIThread() {}
 
 }  // namespace cast_channel