[Media Router] Connection state change listening redesign part 2.

chrome/browser/media/router/presentation_session_state_observer.h

-// Copyright 2015 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 CHROME_BROWSER_MEDIA_ROUTER_PRESENTATION_SESSION_STATE_OBSERVER_H_
-#define CHROME_BROWSER_MEDIA_ROUTER_PRESENTATION_SESSION_STATE_OBSERVER_H_
-
-#include <vector>
-
-#include "base/gtest_prod_util.h"
-#include "chrome/browser/media/router/media_route.h"
-#include "chrome/browser/media/router/media_routes_observer.h"
-#include "content/public/browser/presentation_service_delegate.h"
-
-namespace media_router {
-
-class MediaRouter;
-
-// TODO(imcheng): Remove this class and use PresentationConnectionStateObserver
-// instead (crbug.com/529893).
-// MediaRoutesObserver implementation that allows tracking state changes from
-// multiple presentation sessions and notifying the client via
-// |state_changed_callback|.
-// Clients provide the callback on construction, and incrementally add route
-// IDs to track by calling |OnPresentationSessionConnected| as they are created,
-// which also has the effect of invoking the callback that the session has
-// become connected.
-// When a presentation is disconnected, the callback will be invoked and it
-// will be removed from the tracked set.
-// When the routes no longer need to tracked, |Reset| can be called.
-class PresentationSessionStateObserver : public MediaRoutesObserver {
- public:
-  PresentationSessionStateObserver(
-      const content::SessionStateChangedCallback& state_changed_callback,
-      const MediaRouteIdToPresentationSessionMapping* route_id_to_presentation,
-      MediaRouter* router);
-  ~PresentationSessionStateObserver() override;
-
-  // Called when a presentation with |route_id| has been created in connected
-  // state and invoke the callback.
-  void OnPresentationSessionConnected(const MediaRoute::Id& route_id);
-
-  // Clears the set of presentations being tracked.
-  void Reset();
-
- private:
-  FRIEND_TEST_ALL_PREFIXES(PresentationSessionStateObserverTest,
-                           InvokeCallbackWithDisconnected);
-  FRIEND_TEST_ALL_PREFIXES(PresentationSessionStateObserverTest, Reset);
-
-  // MediaRoutesObserver override
-  void OnRoutesUpdated(const std::vector<MediaRoute>& routes) override;
-
-  // Invokes |state_changed_callback_| with PresentationSessionInfo derived from
-  // |route_id| and |new_state|, if |route_id| is valid.
-  void InvokeCallback(const MediaRoute::Id& route_id,
-                      content::PresentationConnectionState new_state);
-
-  // Route IDs of presentations that are being tracked for state changes.
-  // It is built by adding entries when a presentation is started,
-  // and removing entries when the presentation is no longer in subsequent
-  // route list updates.
-  std::vector<MediaRoute::Id> tracked_route_ids_;
-
-  // Stores previous list of routes observed from MediaRouter.
-  // It is compared against the new observed list of routes for disconnected
-  // routes that are in |tracked_route_ids_|.
-  // TODO(imcheng): A more explicit set of MediaRoutesObserver APIs (e.g.,
-  // OnRoutesClosed) would be helpful here. (crbug.com/508751)
-  std::vector<MediaRoute::Id> previous_route_ids_;
-
-  // Callback to invoke when state change occurs.
-  content::SessionStateChangedCallback state_changed_callback_;
-
-  // Note that while it is declared const to prevent this class from modifying
-  // it, its contents can be changed by the PresentationFrame that owns it.
-  const MediaRouteIdToPresentationSessionMapping* const
-      route_id_to_presentation_;
-
-  DISALLOW_COPY_AND_ASSIGN(PresentationSessionStateObserver);
-};
-
-}  // namespace media_router
-
-#endif  // CHROME_BROWSER_MEDIA_ROUTER_PRESENTATION_SESSION_STATE_OBSERVER_H_