Add unit tests for RTCMTLVideoView.

webrtc/sdk/BUILD.gn

Index: webrtc/sdk/BUILD.gn
diff --git a/webrtc/sdk/BUILD.gn b/webrtc/sdk/BUILD.gn
index 4acf3783f545259ac77f82027932f9ba2a03628d..77621d7a327acde29d64cf686ad51d6b2c584c2c 100644
--- a/webrtc/sdk/BUILD.gn
+++ b/webrtc/sdk/BUILD.gn
@@ -94,6 +94,7 @@ if (is_ios || is_mac) {
 
   rtc_static_library("rtc_sdk_peerconnection_objc") {
     sources = [
+      "objc/Framework/Classes/Metal/RTCMTLNV12Renderer.h",
       "objc/Framework/Classes/RTCAVFoundationVideoCapturerInternal.h",
       "objc/Framework/Classes/RTCAVFoundationVideoCapturerInternal.mm",
       "objc/Framework/Classes/RTCAVFoundationVideoSource+Private.h",
@@ -253,10 +254,14 @@ if (is_ios || is_mac) {
         "objc/Framework/UnitTests/RTCDataChannelConfigurationTest.mm",
         "objc/Framework/UnitTests/RTCIceCandidateTest.mm",
         "objc/Framework/UnitTests/RTCIceServerTest.mm",
+        "objc/Framework/UnitTests/RTCMTLVideoViewTests.mm",
         "objc/Framework/UnitTests/RTCMediaConstraintsTest.mm",
         "objc/Framework/UnitTests/RTCSessionDescriptionTest.mm",
         "objc/Framework/UnitTests/avformatmappertests.mm",
       ]
+      if (current_cpu != "arm64") {
+        sources += [ "objc/Framework/Classes/Metal/RTCMTLVideoView.m" ]
+      }
       deps = [
         ":rtc_sdk_peerconnection_objc",
         "//third_party/ocmock",