iOS SDK 10.0 compatability.

This CL adds support targeting iOS 10 as a min version.

Bug: None
Change-Id: I353a9884eb907e97387553fd73427fd7cb0dbfc2
Reviewed-on: https://webrtc-review.googlesource.com/79921
Reviewed-by: Anders Carlsson <andersc@webrtc.org>
Commit-Queue: Kári Helgason <kthelgason@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23461}

sdk/objc/Framework/Classes/PeerConnection/RTCCameraVideoCapturer.m

@@ -110,7 +110,16 @@ const int64_t kNanosecondsPerSecond = 1000000000;
 }
 
 + (NSArray<AVCaptureDevice *> *)captureDevices {
+#if defined(WEBRTC_IOS) && defined(__IPHONE_10_0) && \
+    __IPHONE_OS_VERSION_MIN_REQUIRED >= __IPHONE_10_0
+  AVCaptureDeviceDiscoverySession *session = [AVCaptureDeviceDiscoverySession
+      discoverySessionWithDeviceTypes:@[ AVCaptureDeviceTypeBuiltInWideAngleCamera ]
+                            mediaType:AVMediaTypeVideo
+                             position:AVCaptureDevicePositionUnspecified];
+  return session.devices;
+#else
   return [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
+#endif
 }
 
 + (NSArray<AVCaptureDeviceFormat *> *)supportedFormatsForDevice:(AVCaptureDevice *)device {