Make video quality test fail cleaner if video hasn't started yet.

chrome/test/data/webrtc/video_extraction.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.
  */
 
 /**
  * The gStartedAt when the capturing begins. Used for timeout adjustments.
  * @private
  */
@@ skipping 18 matching lines @@
  */
 var gFrames = [];
 
 /**
  * We need to skip the first two frames due to timing issues.
  * @private
  */
 var gHasThrownAwayFirstTwoFrames = false;
 
 /**
- * We need this global variable to synchronize with the test how long to run the
- * call between the two peers.
+ * A string to be returned to the test about the current status of capture.
  */
-var gDoneFrameCapturing = false;
+var gCapturingStatus = 'capturing-not-started';
 
 /**
  * Starts the frame capturing.
  *
  * @param {!Object} The video tag from which the height and width parameters are
                     to be extracted.
  * @param {Number} The frame rate at which we would like to capture frames.
  * @param {Number} The duration of the frame capture in seconds.
  */
 function startFrameCapture(videoTag, frameRate, duration) {
   gFrameCaptureInterval = 1000 / frameRate;
   gCaptureDuration = 1000 * duration;
   inputElement = document.getElementById("local-view");
   var width = inputElement.videoWidth;
   var height = inputElement.videoHeight;
+
   // The WebRTC code is free to start in VGA, so make sure that the output video
   // tag scales up to whatever the input size is (otherwise the video quality
   // comparison will go poorly.
   videoTag.width = width;
   videoTag.height = height;
 
   if (width == 0 || height == 0) {
-    throw failTest('Trying to capture from ' + videoTag.id +
-                   ' but it is not playing any video.');
+    // Video must be playing at this point since this function is invoked from
+    // onplay on the <video> tag. See http://crbug.com/625943.
+    gCapturingStatus = 'failed-video-was-0x0-after-onplay'
+    return;
   }
 
   console.log('Received width is: ' + width + ', received height is: ' + height
               + ', capture interval is: ' + gFrameCaptureInterval +
               ', duration is: ' + gCaptureDuration);
+  gCapturingStatus = 'still-capturing';
 
   var remoteCanvas = document.createElement('canvas');
   remoteCanvas.width = width;
   remoteCanvas.height = height;
   document.body.appendChild(remoteCanvas);
 
   gStartedAt = new Date().getTime();
   gFrames = [];
   setTimeout(function() { shoot_(videoTag, remoteCanvas, width, height); },
              gFrameCaptureInterval);
 }
 
 /**
  * Queries if we're done with the frame capturing yet.
  */
 function doneFrameCapturing() {
-  if (gDoneFrameCapturing) {
-    returnToTest('done-capturing');
-  } else {
-    returnToTest('still-capturing');
-  }
+  returnToTest(gCapturingStatus);
 }
 
 /**
  * Retrieves the number of captured frames.
  */
 function getTotalNumberCapturedFrames() {
   returnToTest(gFrames.length.toString());
 }
 
 /**
@@ skipping 59 matching lines @@
   var idealTime = gFrames.length * gFrameCaptureInterval;
   var realTimeElapsed = currentTime - gStartedAt;
   var diff = realTimeElapsed - idealTime;
 
   if (realTimeElapsed < gCaptureDuration) {
     // If duration isn't over shoot_ again.
     setTimeout(function() { shoot_(video, canvas, width, height); },
                gFrameCaptureInterval - diff);
   } else {
     // Done capturing!
-    gDoneFrameCapturing = true;
+    gCapturingStatus = 'done-capturing';
     prepareProgressBar_();
   }
 }
 
 /**
  * @private
  */
 function captureFrame_(video, context, width, height) {
   context.drawImage(video, 0, 0, width, height);
   return context.getImageData(0, 0, width, height);
@@ skipping 11 matching lines @@
 }
 
 /**
  * @private
  */
 function updateProgressBar_(currentFrame) {
   progressBar.innerHTML =
     'Transferring captured frames: ' + '(' + currentFrame + '/' +
     gFrames.length + ')';
 }