[Sheriff] Revert "Deflake preservesPitch tests"

This reverts commit 7b6c400789.

Reason for revert: 

Post this change, preservesPitch seems to consistently fail.

https://ci.chromium.org/p/chromium/builders/ci/Mac10.14%20Tests

Original change's description:
> Deflake preservesPitch tests
> 
> This CL changes preservesPitch tests to wait until the audioElement's
> currentTime is at least 0.5 seconds before trying to detect the pitch.
> Without this check, the test can try to detect the pitch before the
> audio has played enough, which can return a dominant frequency of 0Hz
> and fail the test.
> 
> The CL also makes a few stylistic changes, and fixes an off-by-one error
> in the number of increments used to calculate frequencies.
> 
> Bug: 1096238
> Change-Id: I6e98e172862a47bea1c4026737138293914f7906
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2298281
> Auto-Submit: Thomas Guilbert <tguilbert@chromium.org>
> Commit-Queue: Philip Jägenstedt <foolip@chromium.org>
> Reviewed-by: Philip Jägenstedt <foolip@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#788535}

TBR=tguilbert@chromium.org,foolip@chromium.org

Change-Id: I0042f73ca9c5de7d82be1200794c45b46a003f9b
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1096238
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2299183
Reviewed-by: Roger McFarlane <rogerm@chromium.org>
Commit-Queue: Roger McFarlane <rogerm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#788626}

third_party/blink/web_tests/external/wpt/html/semantics/embedded-content/media-elements/pitch-detector.js

@@ -16,15 +16,14 @@ function getPitchDetector(media, t) {
   sourceNode.connect(analyser);
   analyser.connect(audioContext.destination);
 
-  return () => getPitch(analyser);
+  // Returns the frequency value for the nth FFT bin.
+  var binConverter = (bin) => audioContext.sampleRate*(bin/FFT_SIZE);
+
+  return () => getPitch(analyser, binConverter);
 }
 
-function getPitch(analyser) {
-  // Returns the frequency value for the nth FFT bin.
-  var binConverter = (bin) =>
-    (analyser.context.sampleRate/2)*((bin)/(analyser.frequencyBinCount-1));
-
-  var buf = new Uint8Array(analyser.frequencyBinCount);
+function getPitch(analyser, binConverter) {
+  var buf = new Uint8Array(FFT_SIZE/2);
   analyser.getByteFrequencyData(buf);
   return findDominantFrequency(buf, binConverter);
 }
@@ -41,8 +40,9 @@ function findDominantFrequency(buf, binConverter) {
     }
   }
 
-  // The spread of frequencies within bins is constant and corresponds to
-  // (1/(FFT_SIZE-1))th of the sample rate. Use the value of bin #1 as a
-  // shorthand for that value.
+  // The distance between bins is always constant and corresponds to
+  // (1/FFT_SIZE)th of the sample rate. Use the frequency value of the 1st bin
+  // as the margin directly, instead of calculating an average from the values
+  // of the neighboring bins.
   return { value:binConverter(bin), margin:binConverter(1) };
 }

third_party/blink/web_tests/external/wpt/html/semantics/embedded-content/media-elements/preserves-pitch.html

@@ -56,34 +56,27 @@ function testPreservesPitch(preservesPitch, playbackRate, expectedPitch, descrip
         audio.playbackRate = playbackRate;
         setPreservesPitch(audio, preservesPitch);
 
-        function waitUntil(time) {
-            return new Promise((resolve) => {
-                audio.ontimeupdate = () => {
-                    if (audio.currentTime >= time) {
-                        resolve();
-                    }
-                };
-            });
+        function promiseTimeUpdate() {
+            return new Promise((resolve) => audio.ontimeupdate = resolve);
+        }
+
+        function verifyPitch() {
+            var pitch = detector();
+
+            // 25Hz is larger than the margin we get from 48kHz and 44.1kHz
+            // audio being analyzed by a FFT of size 2048. If we get something
+            // different, there is an error within the test's calculations (or
+            // we might be dealing a larger sample rate).
+            assert_less_than(pitch.margin, 25,
+                "Test error: the margin should be reasonably small.")
+
+            assert_approx_equals(pitch.value, expectedPitch, pitch.margin,
+                "The actual pitch should be close to the expected pitch.");
         }
 
         await test_driver.bless("Play audio element", () => audio.play() )
-
-        // Wait until we have at least played some audio. Otherwise, the
-        // detector might return a pitch of 0Hz.
-        await waitUntil(0.5);
-
-        var pitch = detector();
-
-        // 25Hz is larger than the margin we get from 48kHz and 44.1kHz
-        // audio being analyzed by a FFT of size 2048. If we get something
-        // different, there is an error within the test's calculations (or
-        // we might be dealing a larger sample rate).
-        assert_less_than(pitch.margin, 25,
-            "Test error: the margin should be reasonably small.")
-
-        assert_approx_equals(pitch.value, expectedPitch, pitch.margin,
-            "The actual pitch should be close to the expected pitch.");
-
+          .then(promiseTimeUpdate)
+          .then(verifyPitch);
     }, description);
 }