Better generalize VR test framework

chrome/test/data/android/webvr_instrumentation/resources/webvr_boilerplate.js

Index: chrome/test/data/android/webvr_instrumentation/resources/webvr_boilerplate.js
diff --git a/chrome/test/data/android/webvr_instrumentation/resources/webvr_boilerplate.js b/chrome/test/data/android/webvr_instrumentation/resources/webvr_boilerplate.js
index 4d168c5da45aa2d69f13c35b9c80319fd4ee1c7b..87d6f8335f5982546f622a61d9b68fdcb5d55fe2 100644
--- a/chrome/test/data/android/webvr_instrumentation/resources/webvr_boilerplate.js
+++ b/chrome/test/data/android/webvr_instrumentation/resources/webvr_boilerplate.js
@@ -2,6 +2,15 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// Add additional setup steps to the object from webvr_e2e.js if it exists.
+if (typeof initializationSteps !== "undefined") {
+  initializationSteps["getVRDisplays"] = false;
+} else {
+  // Create here if it doesn't exist so we can access it later without checking
+  // if it's defined.
+  var initializationSteps = {};
+}
+
 var webglCanvas = document.getElementById("webgl-canvas");
 var glAttribs = {
   alpha: false,
@@ -67,10 +76,10 @@ if (navigator.getVRDisplays) {
       vrDisplay = displays[0];
     }
   }).then( () => {
-    vrDisplayPromiseDone = true;
+    initializationSteps["getVRDisplays"] = true;
   });
 } else {
-  vrDisplayPromiseDone = true;
+  initializationSteps["getVRDisplays"] = true;
 }
 
 gl.clearColor(1.0, 0.0, 0.0, 1.0);