text: // 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.
  
  #ifndef REMOTING_HOST_HOST_EXTENSION_SESSION_MANAGER_H_
  #define REMOTING_HOST_HOST_EXTENSION_SESSION_MANAGER_H_
  
  #include <string>
  #include <vector>
  
  #include "base/memory/scoped_ptr.h"
  #include "base/memory/scoped_vector.h"
  
  namespace webrtc {
  class DesktopCapturer;
  }
  
  namespace remoting {
  
  class ClientSessionControl;
  class HostExtension;
  class HostExtensionSession;
  class VideoEncoder;
  
  namespace protocol {
  class ClientStub;
  class ExtensionMessage;
  }
  
  // Helper class used to create and manage a set of HostExtensionSession
  // instances depending upon the set of registered HostExtensions, and the
  // set of capabilities negotiated between client and host.
  class HostExtensionSessionManager {
   public:
    typedef std::vector<HostExtension*> HostExtensions;
  
    // Creates an extension manager for the specified |extensions|.
    HostExtensionSessionManager(const HostExtensions& extensions,
                                ClientSessionControl* client_session_control);
    virtual ~HostExtensionSessionManager();
  
    // Returns the union of all capabilities supported by registered extensions.
    std::string GetCapabilities() const;
  
    // Calls the corresponding hook functions for each extension, to allow them
    // to wrap or replace video pipeline components. Only extensions which return
    // true from ModifiesVideoPipeline() will be called.
    // The order in which extensions are called is undefined.
    void OnCreateVideoCapturer(scoped_ptr<webrtc::DesktopCapturer>* capturer);
    void OnCreateVideoEncoder(scoped_ptr<VideoEncoder>* encoder);
  
    // Handles completion of authentication and capabilities negotiation, creating
    // the set of HostExtensionSessions to match the client's capabilities.
    void OnNegotiatedCapabilities(protocol::ClientStub* client_stub,
                                  const std::string& capabilities);
  
    // Passes |message| to each HostExtensionSession in turn until the message
    // is handled, or none remain. Returns true if the message was handled.
    // It is not valid for more than one extension to handle the same message.
    bool OnExtensionMessage(const protocol::ExtensionMessage& message);
  
   private:
    typedef ScopedVector<HostExtensionSession> HostExtensionSessions;
  
    // Passed to HostExtensionSessions to allow them to send messages,
    // disconnect the session, etc.
    ClientSessionControl* client_session_control_;
    protocol::ClientStub* client_stub_;
  
    // The HostExtensions to instantiate for the session, if it reaches the
    // authenticated state.
    HostExtensions extensions_;
  
    // The instantiated HostExtensionSessions, used to handle extension messages.
    HostExtensionSessions extension_sessions_;
  
    DISALLOW_COPY_AND_ASSIGN(HostExtensionSessionManager);
  };
  
  }  // namespace remoting
  
  #endif  // REMOTING_HOST_HOST_EXTENSION_SESSION_MANAGER_H_
  