Add some more test cases for RTCCVPixelBuffer.

Also fix rendering of certain i420 buffers in debug quicklook.

Bug: None
Change-Id: I793915c3a5a1fcb4cd7b24383d1579655e9a7c28
Reviewed-on: https://webrtc-review.googlesource.com/72080
Reviewed-by: Kári Helgason <kthelgason@webrtc.org>
Commit-Queue: Anders Carlsson <andersc@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23005}

sdk/objc/Framework/Classes/Video/RTCI420Buffer.mm

@@ -127,9 +127,9 @@
                      _i420Buffer->DataV(),
                      _i420Buffer->StrideV(),
                      ctxData,
-                     _i420Buffer->width() * 4,
-                     _i420Buffer->width(),
-                     _i420Buffer->height());
+                     CGBitmapContextGetBytesPerRow(c),
+                     CGBitmapContextGetWidth(c),
+                     CGBitmapContextGetHeight(c));
 
   UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
   UIGraphicsEndImageContext();