Revert of Removed duplicated JS hasVideoInputDeviceOnSystem() test helper

chrome/test/data/webrtc/media_devices.js

Index: chrome/test/data/webrtc/media_devices.js
diff --git a/chrome/test/data/webrtc/media_devices.js b/chrome/test/data/webrtc/media_devices.js
index 38a7238ccef3e3e907b6af1936af3be4ea1bc4e6..356184e3b5e6dbf75e148f89f0a5be47aba36613 100644
--- a/chrome/test/data/webrtc/media_devices.js
+++ b/chrome/test/data/webrtc/media_devices.js
@@ -27,3 +27,27 @@
   });
 }
 
+/**
+ * Queries for video input devices on the current system using the
+ * getSources API.
+ *
+ * This does not guarantee that a getUserMedia with video will succeed, as the
+ * camera could be busy for instance.
+ *
+ * Returns has-video-input-device to the test if there is a webcam available,
+ * no-video-input-devices otherwise.
+ */
+function hasVideoInputDeviceOnSystem() {
+  MediaStreamTrack.getSources(function(devices) {
+    var hasVideoInputDevice = false;
+    devices.forEach(function(device) {
+      if (device.kind == 'video')
+        hasVideoInputDevice = true;
+    });
+
+    if (hasVideoInputDevice)
+      returnToTest('has-video-input-device');
+    else
+      returnToTest('no-video-input-devices');
+  });
+}