Media Remoting Clean-up: Less-redundant naming, style consistency, etc.

media/remoting/rpc/rpc_broker.h

-// Copyright 2016 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.
-
-#ifndef MEDIA_REMOTING_RPC_RPC_BROKER_H_
-#define MEDIA_REMOTING_RPC_RPC_BROKER_H_
-
-#include <map>
-#include <memory>
-#include <string>
-#include <vector>
-
-#include "base/callback.h"
-#include "base/macros.h"
-#include "base/memory/weak_ptr.h"
-#include "base/threading/thread_checker.h"
-#include "media/remoting/remoting_rpc_message.pb.h"
-
-namespace media {
-namespace remoting {
-
-// Predefined invalid handle value for RPC message.
-constexpr int kInvalidHandle = -1;
-
-// Predefined handle value for RPC messages related to initialization.
-constexpr int kReceiverHandle = 0;
-
-// Utility class to process incoming and outgoing RPC message to desired
-// components on both end points. On sender side, for outgoing message, sender
-// sends RPC message with associated handle value. On receiver side, for
-// component which is interested in this RPC message has to register itself to
-// RpcBroker. Before the RPC transmission starts, both sender and receiver need
-// to negotiate the handle value in the existing RPC communication channel using
-// handle kReceiverHandle.
-//
-// The class doesn't actually send RPC message to remote end point. Actual
-// sender needs to set SendMessageCallback to RpcBroker. The class doesn't
-// actually receive RPC message from the remote end point, either. Actually
-// receiver needs to call ProcessMessageFromRemote() when RPC message is
-// received. RpcBroker will distribute each RPC message to the components based
-// on the handle value in the RPC message.
-//
-// Note this is single-threaded class running on main thread. It provides
-// WeakPtr() for caller to post tasks to the main thread.
-class RpcBroker {
- public:
-  using SendMessageCallback =
-      base::Callback<void(std::unique_ptr<std::vector<uint8_t>>)>;
-  explicit RpcBroker(const SendMessageCallback& send_message_cb);
-  ~RpcBroker();
-
-  // Get unique handle value (larger than 0) for RPC message handles.
-  int GetUniqueHandle();
-
-  using ReceiveMessageCallback =
-      base::Callback<void(std::unique_ptr<pb::RpcMessage>)>;
-  // Register a component to receive messages via the given
-  // ReceiveMessageCallback. |handle| is a unique handle value provided by a
-  // prior call to GetUniqueHandle() and is used to reference the component in
-  // the RPC messages. The receiver can then use it to direct an RPC message
-  // back to a specific component.
-  void RegisterMessageReceiverCallback(int handle,
-                                       const ReceiveMessageCallback& callback);
-  // Allows components to unregister in order to stop receiving message.
-  void UnregisterMessageReceiverCallback(int handle);
-
-  // Allows RpcBroker to distribute incoming RPC message to desired components.
-  void ProcessMessageFromRemote(std::unique_ptr<pb::RpcMessage> message);
-  // Sends RPC message to remote end point. The actually sender which sets
-  // SendMessageCallback to RpcBrokwer will receive RPC message to do actual
-  // data transmission.
-  void SendMessageToRemote(std::unique_ptr<pb::RpcMessage> message);
-
-  // Gets weak pointer of RpcBroker. This allows callers to post tasks to
-  // RpcBroker on the main thread.
-  base::WeakPtr<RpcBroker> GetWeakPtr();
-
-  // Overwrites |send_message_cb_|. This is used only for test purposes.
-  void SetMessageCallbackForTesting(const SendMessageCallback& send_message_cb);
-
- private:
-  // Checks that all method calls occur on the same thread.
-  base::ThreadChecker thread_checker_;
-
-  // Next unique handle to return from GetUniqueHandle().
-  int next_handle_;
-
-  // Maps to hold handle value associated to MessageReceiver.
-  std::map<int, ReceiveMessageCallback> receive_callbacks_;
-
-  // Callback that is run to send a serialized message.
-  SendMessageCallback send_message_cb_;
-
-  base::WeakPtrFactory<RpcBroker> weak_factory_;
-
-  DISALLOW_COPY_AND_ASSIGN(RpcBroker);
-};
-
-}  // namespace remoting
-}  // namespace media
-
-#endif  // MEDIA_REMOTING_RPC_RPC_BROKER_H_