Revert of Add Metal video view in AppRTCMobile and metal availability macro.

webrtc/examples/objc/AppRTCMobile/ios/ARDVideoCallView.m

Index: webrtc/examples/objc/AppRTCMobile/ios/ARDVideoCallView.m
diff --git a/webrtc/examples/objc/AppRTCMobile/ios/ARDVideoCallView.m b/webrtc/examples/objc/AppRTCMobile/ios/ARDVideoCallView.m
index 869d29cb6c4b02d4191a367160da11bf96bdde79..6e5fc597e9fc2defaba07e8dc02dad4eafb2f9b6 100644
--- a/webrtc/examples/objc/AppRTCMobile/ios/ARDVideoCallView.m
+++ b/webrtc/examples/objc/AppRTCMobile/ios/ARDVideoCallView.m
@@ -11,10 +11,6 @@
 #import "ARDVideoCallView.h"
 
 #import <AVFoundation/AVFoundation.h>
-
-#import <WebRTC/RTCEAGLVideoView.h>
-#import <WebRTC/RTCMTLVideoView.h>
-
 #import "UIImage+ARDUtilities.h"
 
 static CGFloat const kButtonPadding = 16;
@@ -42,15 +38,8 @@
 
 - (instancetype)initWithFrame:(CGRect)frame {
   if (self = [super initWithFrame:frame]) {
-
-#if defined(RTC_SUPPORTS_METAL)
-    _remoteVideoView = [[RTCMTLVideoView alloc] initWithFrame:CGRectZero];
-#else
-    RTCEAGLVideoView *remoteView = [[RTCEAGLVideoView alloc] initWithFrame:CGRectZero];
-    remoteView.delegate = self;
-    _remoteVideoView = remoteView;
-#endif
-
+    _remoteVideoView = [[RTCEAGLVideoView alloc] initWithFrame:CGRectZero];
+    _remoteVideoView.delegate = self;
     [self addSubview:_remoteVideoView];
 
     _localVideoView = [[RTCCameraPreviewView alloc] initWithFrame:CGRectZero];