iOS: Add new RTCVideoSource interface

webrtc/sdk/objc/Framework/Headers/WebRTC/RTCVideoSource.h

Index: webrtc/sdk/objc/Framework/Headers/WebRTC/RTCVideoSource.h
diff --git a/webrtc/sdk/objc/Framework/Headers/WebRTC/RTCVideoSource.h b/webrtc/sdk/objc/Framework/Headers/WebRTC/RTCVideoSource.h
index 96bb6f369973c55ea7345d8528b368fc6cebb4e1..27a58f27cb782eb87d91353b2a45ae1ca06086e4 100644
--- a/webrtc/sdk/objc/Framework/Headers/WebRTC/RTCVideoSource.h
+++ b/webrtc/sdk/objc/Framework/Headers/WebRTC/RTCVideoSource.h
@@ -12,14 +12,30 @@
 
 #import <WebRTC/RTCMacros.h>
 #import <WebRTC/RTCMediaSource.h>
+#import <WebRTC/RTCVideoCapturer.h>
 
 NS_ASSUME_NONNULL_BEGIN
 
 RTC_EXPORT
-@interface RTCVideoSource : RTCMediaSource
+
+@interface RTCVideoSource : RTCMediaSource <RTCVideoCapturerDelegate>
 
 - (instancetype)init NS_UNAVAILABLE;
 
+// RTCVideoCapturerDelegate protocol implementation.
+- (void)capturer:(RTCVideoCapturer*)capturer
+    didCaptureVideoFrame:(RTCVideoFrame*)frame;
+
+/**
+ * Calling this function will cause frames to be scaled down to the
+ * requested resolution. Also, frames will be cropped to match the
+ * requested aspect ratio, and frames will be dropped to match the
+ * requested fps. The requested aspect ratio is orientation agnostic and
+ * will be adjusted to maintain the input orientation, so it doesn't
+ * matter if e.g. 1280x720 or 720x1280 is requested.
+ */
+- (void)adaptOutputFormatToWidth:(int)width height:(int)height fps:(int)fps;
+
 @end
 
 NS_ASSUME_NONNULL_END