Add WebVR WebVR E2E test capabilities via Android instrumentation

chrome/test/data/android/webvr_instrumentation/resources/webvr_e2e.js

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+var testPassed = false;
+var resultString = "";
+var asyncCounter = 0;
+var javascriptDone = false;
+var vrDisplayPromiseDone = false;
+
+function finishJavascriptStep() {
+  javascriptDone = true;
+}
+
+function checkResultsForFailures(tests, harness_status) {
+  testPassed = true;
+  if (harness_status["status"] != 0) {
+    testPassed = false;
+    resultString += "Harness failed due to " +
+                    (harness_status["status"] == 1 ? "error" : "timeout")
+                    + ". ";
+  }
+  for (var test in tests) {
+    let passed = (tests[test]["status"] == 0);
+    if (!passed) {
+      testPassed = false;
+      resultString += "FAIL ";
+    } else {
+      resultString += "PASS ";
+    }
+    resultString += tests[test]["name"] +
+                    (passed ? "" : (": " + tests[test]["message"])) +
+                    ". ";
+  }
+}
+
+add_completion_callback( (tests, harness_status) => {
+  checkResultsForFailures(tests, harness_status);
+  console.debug("Test result: " + (testPassed ? "Pass" : "Fail"));
+  console.debug("Test result string: " + resultString);
+  finishJavascriptStep();
+});