VideoCaptureDeviceAVFoundationLegacy: revert to legacy state.

This change reverts VideoCaptureDeviceAVFoundationLegacy to the
implementation in video_capture_device_avfoundation at rev 86ee59bf,
permitting further evolution in VideoCaptureDeviceAVFoundation while
retaining the legacy implementation accessible by running with
kAVFoundationCaptureV2 disabled.

Bug: chromium:1126690
Change-Id: I5be7e3dffc4b72d51e69710651fd3a46fb2a9860
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2404166
Commit-Queue: Markus Handell <handellm@google.com>
Reviewed-by: ccameron <ccameron@chromium.org>
Cr-Commit-Position: refs/heads/master@{#806475}

media/capture/video/mac/video_capture_device_avfoundation_legacy_mac.h

@@ -15,6 +15,42 @@
 #include "media/capture/video/video_capture_device.h"
 #include "media/capture/video_capture_types.h"
 
+namespace media {
+class VideoCaptureDeviceMac;
+}
+
+// Class used by VideoCaptureDeviceMac (VCDM) for video and image capture using
+// AVFoundation API. This class lives inside the thread created by its owner
+// VCDM.
+//
+//  * Clients (VCDM) should call +deviceNames to fetch the list of devices
+//    available in the system; this method returns the list of device names that
+//    have to be used with -setCaptureDevice:.
+//  * Previous to any use, clients (VCDM) must call -initWithFrameReceiver: to
+//    initialise an object of this class and register a |frameReceiver_|.
+//  * Frame receiver registration or removal can also happen via explicit call
+//    to -setFrameReceiver:. Re-registrations are safe and allowed, even during
+//    capture using this method.
+//  * Method -setCaptureDevice: must be called at least once with a device
+//    identifier from +deviceNames. Creates all the necessary AVFoundation
+//    objects on first call; it connects them ready for capture every time.
+//    This method should not be called during capture (i.e. between
+//    -startCapture and -stopCapture).
+//  * -setCaptureWidth:height:frameRate: is called if a resolution or frame rate
+//    different than the by default one set by -setCaptureDevice: is needed.
+//    This method should not be called during capture. This method must be
+//    called after -setCaptureDevice:.
+//  * -startCapture registers the notification listeners and starts the
+//    capture. The capture can be stop using -stopCapture. The capture can be
+//    restarted and restoped multiple times, reconfiguring or not the device in
+//    between.
+//  * -setCaptureDevice can be called with a |nil| value, case in which it stops
+//    the capture and disconnects the library objects. This step is not
+//    necessary.
+//  * Deallocation of the library objects happens gracefully on destruction of
+//    the VideoCaptureDeviceAVFoundation object.
+//
+//
 @interface VideoCaptureDeviceAVFoundationLegacy
     : NSObject <AVCaptureVideoDataOutputSampleBufferDelegate,
                 VideoCaptureDeviceAVFoundationProtocol> {
@@ -24,9 +60,6 @@
   int _frameHeight;
   float _frameRate;
 
-  // The capture format that best matches the above attributes.
-  base::scoped_nsobject<AVCaptureDeviceFormat> _bestCaptureFormat;
-
   base::Lock _lock;  // Protects concurrent setting and using |frameReceiver_|.
   media::VideoCaptureDeviceAVFoundationFrameReceiver* _frameReceiver;  // weak.
 
@@ -40,18 +73,55 @@
 
   // An AVDataOutput specialized for taking pictures out of |captureSession_|.
   base::scoped_nsobject<AVCaptureStillImageOutput> _stillImageOutput;
-  size_t _takePhotoStartedCount;
-  size_t _takePhotoPendingCount;
-  size_t _takePhotoCompletedCount;
-  bool _stillImageOutputWarmupCompleted;
-  std::unique_ptr<base::WeakPtrFactory<VideoCaptureDeviceAVFoundationLegacy>>
-      _weakPtrFactoryForTakePhoto;
-
-  // For testing.
-  base::RepeatingCallback<void()> _onStillImageOutputStopped;
 
-  scoped_refptr<base::SingleThreadTaskRunner> _mainThreadTaskRunner;
+  base::ThreadChecker _main_thread_checker;
 }
+
+// Returns a dictionary of capture devices with friendly name and unique id.
++ (NSDictionary*)deviceNames;
+
+// Retrieve the capture supported formats for a given device |descriptor|.
++ (void)getDevice:(const media::VideoCaptureDeviceDescriptor&)descriptor
+    supportedFormats:(media::VideoCaptureFormats*)formats;
+
+// Initializes the instance and the underlying capture session and registers the
+// frame receiver.
+- (id)initWithFrameReceiver:
+    (media::VideoCaptureDeviceAVFoundationFrameReceiver*)frameReceiver;
+
+// Sets the frame receiver.
+- (void)setFrameReceiver:
+    (media::VideoCaptureDeviceAVFoundationFrameReceiver*)frameReceiver;
+
+// Sets which capture device to use by name, retrieved via |deviceNames|. Once
+// the deviceId is known, the library objects are created if needed and
+// connected for the capture, and a by default resolution is set. If deviceId is
+// nil, then the eventual capture is stopped and library objects are
+// disconnected. Returns YES on success, NO otherwise. If the return value is
+// NO, an error message is assigned to |outMessage|. This method should not be
+// called during capture.
+- (BOOL)setCaptureDevice:(NSString*)deviceId
+            errorMessage:(NSString**)outMessage;
+
+// Configures the capture properties for the capture session and the video data
+// output; this means it MUST be called after setCaptureDevice:. Return YES on
+// success, else NO.
+- (BOOL)setCaptureHeight:(int)height
+                   width:(int)width
+               frameRate:(float)frameRate;
+
+// Starts video capturing and register the notification listeners. Must be
+// called after setCaptureDevice:, and, eventually, also after
+// setCaptureHeight:width:frameRate:. Returns YES on success, NO otherwise.
+- (BOOL)startCapture;
+
+// Stops video capturing and stops listening to notifications.
+- (void)stopCapture;
+
+// Takes a photo. This method should only be called between -startCapture and
+// -stopCapture.
+- (void)takePhoto;
+
 @end
 
-#endif  // MEDIA_CAPTURE_VIDEO_MAC_VIDEO_CAPTURE_DEVICE_AVFOUNDATION_LEGACY_MAC_H_
+#endif  // MEDIA_CAPTURE_VIDEO_MAC_VIDEO_CAPTURE_DEVICE_AVFOUNDATION_MAC_H_