Revert of Removed duplicated JS hasVideoInputDeviceOnSystem() test helper

content/test/data/media/webrtc_test_utilities.js

Index: content/test/data/media/webrtc_test_utilities.js
diff --git a/content/test/data/media/webrtc_test_utilities.js b/content/test/data/media/webrtc_test_utilities.js
index aa11a975912478108af4879dd16c6d35000788fe..d551b8a128906c1c54901e292ea26aff1064f3c3 100644
--- a/content/test/data/media/webrtc_test_utilities.js
+++ b/content/test/data/media/webrtc_test_utilities.js
@@ -263,3 +263,19 @@
   }
 }
 
+// Returns has-video-input-device to the test if there's a webcam available on
+// the system.
+function hasVideoInputDeviceOnSystem() {
+  MediaStreamTrack.getSources(function(devices) {
+    var hasVideoInputDevice = false;
+    devices.forEach(function(device) {
+      if (device.kind == 'video')
+        hasVideoInputDevice = true;
+    });
+
+    if (hasVideoInputDevice)
+      sendValueToTest('has-video-input-device');
+    else
+      sendValueToTest('no-video-input-devices');
+  });
+}