Added video capture capabilities retrieval and caching to VideoCaptureManager

content/browser/renderer_host/media/video_capture_manager.h

 // Copyright (c) 2012 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.
 
 // VideoCaptureManager is used to open/close, start/stop, enumerate available
 // video capture devices, and manage VideoCaptureController's.
 // All functions are expected to be called from Browser::IO thread. Some helper
 // functions (*OnDeviceThread) will dispatch operations to the device thread.
 // VideoCaptureManager will open OS dependent instances of VideoCaptureDevice.
 // A device can only be opened once.
@@ skipping 41 matching lines @@
   virtual void Close(int capture_session_id) OVERRIDE;
 
   // Used by unit test to make sure a fake device is used instead of a real
   // video capture device. Due to timing requirements, the function must be
   // called before EnumerateDevices and Open.
   void UseFakeDevice();
 
   // Called by VideoCaptureHost to locate a capture device for |capture_params|,
   // adding the Host as a client of the device's controller if successful. The
   // value of |capture_params.session_id| controls which device is selected;
-  // this value should be a session id previously returned by Open().
+  // this value should be a session id previously returned by Open(). The device
+  // capabilities are reduced to |capture_params|.
   //
   // If the device is not already started (i.e., no other client is currently
   // capturing from this device), this call will cause a VideoCaptureController
   // and VideoCaptureDevice to be created, possibly asynchronously.
   //
   // On success, the controller is returned via calling |done_cb|, indicating
   // that the client was successfully added. A NULL controller is passed to
   // the callback on failure.
   void StartCaptureForClient(const media::VideoCaptureParams& capture_params,
                              base::ProcessHandle client_render_process,
                              VideoCaptureControllerID client_id,
                              VideoCaptureControllerEventHandler* client_handler,
                              const DoneCB& done_cb);
 
   // Called by VideoCaptureHost to remove |client_handler|. If this is the last
   // client of the device, the |controller| and its VideoCaptureDevice may be
   // destroyed. The client must not access |controller| after calling this
   // function.
   void StopCaptureForClient(VideoCaptureController* controller,
                             VideoCaptureControllerID client_id,
                             VideoCaptureControllerEventHandler* client_handler);
 
+  // Retrieve the available capture capabilities for a particular device. The

[no longer working on chromium, 2013/11/13 16:20:22]

nit, Retrieves

+  // capabilities are cached during device(s) enumeration and updated as clients
+  // open/close the device(s).
+  void GetDeviceCapabilities(int capture_session_id,
+                             media::VideoCaptureCapabilities* capabilities);
+
  private:
   virtual ~VideoCaptureManager();
   struct DeviceEntry;
 
+  // This data structure is a convenient wrap of a devices' name and associated
+  // video capture capabilities, and a flag that indicates if in use.
+  struct DeviceInfo {
+    DeviceInfo();
+    DeviceInfo(const media::VideoCaptureDevice::Name& name,
+               const media::VideoCaptureCapabilities& capabilities);
+    ~DeviceInfo();
+
+    bool device_in_use;
+    media::VideoCaptureDevice::Name name;
+    media::VideoCaptureCapabilities capabilities;
+  };
+  typedef std::vector<DeviceInfo> DevicesInfo;
+
   // Check to see if |entry| has no clients left on its controller. If so,
   // remove it from the list of devices, and delete it asynchronously. |entry|
   // may be freed by this function.
   void DestroyDeviceEntryIfNoClients(DeviceEntry* entry);
 
   // Helpers to report an event to our Listener.
   void OnOpened(MediaStreamType type, int capture_session_id);
   void OnClosed(MediaStreamType type, int capture_session_id);
-  void OnDevicesEnumerated(MediaStreamType stream_type,
-                           const media::VideoCaptureDevice::Names& names);
+  void OnDeviceNamesAndCapabilitiesEnumerated(
+      MediaStreamType stream_type,
+      const DevicesInfo& new_devices_info_cache);
 
   // Find a DeviceEntry by its device ID and type, if it is already opened.
   DeviceEntry* GetDeviceEntryForMediaStreamDevice(
       const MediaStreamDevice& device_info);
 
   // Find a DeviceEntry entry for the indicated session, creating a fresh one
   // if necessary. Returns NULL if the session id is invalid.
   DeviceEntry* GetOrCreateDeviceEntry(int capture_session_id);
 
   // Find the DeviceEntry that owns a particular controller pointer.
   DeviceEntry* GetDeviceEntryForController(
       const VideoCaptureController* controller);
 
   bool IsOnDeviceThread() const;
 
-  // Queries and returns the available device IDs.
-  media::VideoCaptureDevice::Names GetAvailableDevicesOnDeviceThread(
-      MediaStreamType stream_type);
+  // Queries the Names of the devices in the system; the capabilities of the new
+  // devices are also queried, and consolidated with the copy of the local
+  // device info cache passed. The consolidated list of devices+capabilities is
+  // returned.
+  DevicesInfo GetAvailableDevicesAndCapabilitiesOnDeviceThread(
+      MediaStreamType stream_type,
+      const DevicesInfo& old_device_info_cache);
 
   // Create and Start a new VideoCaptureDevice, storing the result in
   // |entry->video_capture_device|. Ownership of |client| passes to
   // the device.
   void DoStartDeviceOnDeviceThread(
       DeviceEntry* entry,
       const media::VideoCaptureCapability& capture_params,
       scoped_ptr<media::VideoCaptureDevice::Client> client);
 
   // Stop and destroy the VideoCaptureDevice held in
   // |entry->video_capture_device|.
   void DoStopDeviceOnDeviceThread(DeviceEntry* entry);
 
+  DeviceInfo* FindDeviceInfoById(const std::string& id,
+                                 DevicesInfo& device_vector);
+
   // The message loop of media stream device thread, where VCD's live.
   scoped_refptr<base::MessageLoopProxy> device_loop_;
 
   // Only accessed on Browser::IO thread.
   MediaStreamProviderListener* listener_;
   int new_capture_session_id_;
 
   // An entry is kept in this map for every session that has been created via
   // the Open() entry point. The keys are session_id's. This map is used to
   // determine which device to use when StartCaptureForClient() occurs. Used
@@ skipping 20 matching lines @@
 
     // The controller. Only used from the IO thread.
     scoped_ptr<VideoCaptureController> video_capture_controller;
 
     // The capture device. Only used from the device thread.
     scoped_ptr<media::VideoCaptureDevice> video_capture_device;
   };
   typedef std::set<DeviceEntry*> DeviceEntries;
   DeviceEntries devices_;
 
+  // Local cache of the enumerated video capture devices' names and capture
+  // capabilities. A snapshot of the current devices and their capabilities is
+  // composed in GetAvailableDevicesAndCapabilitiesOnDeviceThread() --coming
+  // from EnumerateDevices()--, and this snapshot is used to update this list in
+  // OnDeviceNamesAndCapabilitiesEnumerated(). The flag |device_in_use_| is
+  // updated in StartCaptureForClient() and StopCaptureForClient() (if the
+  // device is not in use anymore).
+  DevicesInfo devices_info_cache_;
+
   // Set to true if using fake video capture devices for testing, false by
   // default. This is only used for the MEDIA_DEVICE_VIDEO_CAPTURE device type.
   bool use_fake_device_;
 
-  // We cache the enumerated video capture devices in
-  // GetAvailableDevicesOnDeviceThread() and then later look up the requested ID
-  // when a device is created in DoStartDeviceOnDeviceThread(). Used only on the
-  // device thread.
-  media::VideoCaptureDevice::Names video_capture_devices_;
-
   DISALLOW_COPY_AND_ASSIGN(VideoCaptureManager);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_VIDEO_CAPTURE_MANAGER_H_