Re-enable local video test with better logging and higher tolerance.

The test appears to get stuck on waiting for black frames. This patch
adds some logging so we perhaps can learn more where in the image we
find the nonblack pixels. Also trying to increase tolerance for
rounding errors somewhat to see if that helps.

BUG=477498

Review URL: https://codereview.chromium.org/1108803002

Cr-Commit-Position: refs/heads/master@{#329616}

content/browser/media/webrtc_browsertest.cc

@@ -144,9 +144,15 @@ IN_PROC_BROWSER_TEST_F(MAYBE_WebRtcBrowserTest,
 }
 
 // Flaky on TSAN v2. http://crbug.com/408006
-// Flaky everywhere: http://crbug.com/477498
+#if defined(THREAD_SANITIZER)
+#define MAYBE_CanSetupVideoCallAndDisableLocalVideo \
+  DISABLED_CanSetupVideoCallAndDisableLocalVideo
+#else
+#define MAYBE_CanSetupVideoCallAndDisableLocalVideo \
+  CanSetupVideoCallAndDisableLocalVideo
+#endif
 IN_PROC_BROWSER_TEST_F(MAYBE_WebRtcBrowserTest,
-                       DISABLED_CanSetupVideoCallAndDisableLocalVideo) {
+                       MAYBE_CanSetupVideoCallAndDisableLocalVideo) {
   const std::string javascript =
       "callAndDisableLocalVideo({video: true});";
   MakeTypicalPeerConnectionCall(javascript);

content/test/data/media/webrtc_test_utilities.js

@@ -66,9 +66,14 @@ function detectVideo(videoElementName, predicate, callback) {
   var width = VIDEO_TAG_WIDTH;
   var height = VIDEO_TAG_HEIGHT;
   var videoElement = $(videoElementName);
-  var canvas = $(videoElementName + '-canvas');
   var oldPixels = [];
+  var startTimeMs = new Date().getTime();
   var waitVideo = setInterval(function() {
+    var canvas = $(videoElementName + '-canvas');
+    if (canvas == null) {
+      console.log('Waiting for ' + videoElementName + '-canvas' + ' to appear');
+      return;
+    }
     var context = canvas.getContext('2d');
     context.drawImage(videoElement, 0, 0, width, height);
     var pixels = context.getImageData(0, 0 , width, height / 3).data;
@@ -82,6 +87,12 @@ function detectVideo(videoElementName, predicate, callback) {
       callback(videoElement.videoWidth, videoElement.videoHeight);
     }
     oldPixels = pixels;
+
+    var elapsedTime = new Date().getTime() - startTimeMs;
+    if (elapsedTime > 3000) {
+      startTimeMs = new Date().getTime();
+      console.log('Still waiting for video to satisfy ' + predicate.toString());
+    }
   }, 200);
 }
 
@@ -186,12 +197,19 @@ function isVideoPlaying(pixels, previousPixels) {
   return false;
 }
 
+// Pixels is an array where pixels[0] is the R value for the first pixel,
+// pixels[1] is the G value, and so on.
 function isVideoBlack(pixels) {
   for (var i = 0; i < pixels.length; i++) {
-    // |pixels| is in RGBA. Ignore the alpha channel.
-    // We allow it to be off by 1, to account for rounding errors in YUV
-    // conversion.
-    if (pixels[i] != 0 && pixels[i] != 1 && (i + 1) % 4 != 0) {
+    if ((i + 1) % 4 == 0) {
+      // Ignore the alpha channel.
+      continue;
+    }
+
+    // A black pixel has 0 for R,G and B but allow a bit more here to account
+    // for rounding errors in libyuv.
+    if (pixels[i] > 3) {
+      console.log('Found nonblack pixel at ' + i + ', was ' + pixels[i]);
       return false;
     }
   }