Make WebRtcWebcamBrowserTest fail faster.

chrome/test/data/webrtc/getusermedia.js

 /**
  * Copyright (c) 2012 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.
  */
 
 /**
  * See http://dev.w3.org/2011/webrtc/editor/getusermedia.html for more
  * information on getUserMedia.
  */
@@ skipping 36 matching lines @@
  *
  * @param {!object} constraints Defines what to be requested, with mandatory
  *     and optional constraints defined. The contents of this parameter depends
  *     on the WebRTC version.
  */
 function doGetUserMedia(constraints) {
   if (!getUserMedia) {
     returnToTest('Browser does not support WebRTC.');
     return;
   }
-  debug('Requesting doGetUserMedia: constraints: ' + constraints);
+  debug('Requesting doGetUserMedia: constraints: ' +
+        JSON.stringify(constraints, null, 0).replace(/[\r\n]/g, ''));
   getUserMedia(constraints,
                function(stream) {
                  ensureGotAllExpectedStreams_(stream, constraints);
                  getUserMediaOkCallback_(stream);
                },
                getUserMediaFailedCallback_);
   returnToTest('ok-requested');
 }
 
 /**
  * Must be called after calling doGetUserMedia.
  * @return {string} Returns not-called-yet if we have not yet been called back
  *     by WebRTC. Otherwise it returns either ok-got-stream or
  *     failed-with-error-x (where x is the error code from the error
  *     callback) depending on which callback got called by WebRTC.
  */
 function obtainGetUserMediaResult() {
   returnToTest(gRequestWebcamAndMicrophoneResult);
-  return gRequestWebcamAndMicrophoneResult;
+  var ret = gRequestWebcamAndMicrophoneResult;
+  // Reset for the next call.
+  gRequestWebcamAndMicrophoneResult = 'not-called-yet';

[tommi (sloooow) - chröme, 2015/04/26 10:55:02]

The problem we were hitting here is that when doing two gUM calls in a row, the
script would return the result from the first run for the second call.

[phoglund_chromium, 2015/04/27 07:46:48]

Good catch. It's possible the re-set should actually be in doGetUserMedia, but I
think the calling code doesn't rely on getting the same answer several times.

+  return ret;
 }
 
 /**
  * Stops all tracks of the last acquired local stream.
  */
 function stopLocalStream() {
   if (gLocalStream == null)
     throw failTest('Tried to stop local stream, ' +
                    'but media access is not granted.');
 
@@ skipping 72 matching lines @@
  * @param {NavigatorUserMediaError} error Error containing details.
  */
 function getUserMediaFailedCallback_(error) {
   // Translate from the old error to the new. Remove when rename fully deployed.
   var errorName = error.name;
 
   debug('GetUserMedia FAILED: Maybe the camera is in use by another process?');
   gRequestWebcamAndMicrophoneResult = 'failed-with-error-' + errorName;
   debug(gRequestWebcamAndMicrophoneResult);
 }