third_party/WebKit/LayoutTests/media/video-controls-hidden-audio.html

<video controls></video>
<p>Test that hiding volume / mute buttons works as expected.</p>
<script src=media-file.js></script>
<!-- TODO(foolip): Convert test to testharness.js. crbug.com/588956
     (Please avoid writing new tests using video-test.js) -->
<script src=video-test.js></script>
<script src=media-controls.js></script>
<script>
    video.src = findMediaFile("video", "content/test");
    run("video.load()");
    waitForEvent("canplaythrough", function () {
        // Enable hidden audio preferences to take effect.
        run("window.internals.setAllowHiddenVolumeControls(video, true)");
        // Request non-hidden audio controls.
        run("window.internals.settings.setPreferHiddenVolumeControls(false)");
        run("video.muted = false");
        muteButton = mediaControlsButton(video, "mute-button");
        volumeSlider = mediaControlsButton(video, "volume-slider");

        // Make sure that both are visible.
        testExpected("getComputedStyle(muteButton).display", "none", '!=');
        testExpected("getComputedStyle(volumeSlider).display", "none", '!=');

        // Switch to muted video.  Both should still be visible.
        run("video.muted = true");
        testExpected("getComputedStyle(muteButton).display", "none", '!=');
        testExpected("getComputedStyle(volumeSlider).display", "none", '!=');

        run("window.internals.settings.setPreferHiddenVolumeControls(true)");

        // Switch back to unmuted video.
        run("video.muted = false");

        testExpected("getComputedStyle(muteButton).display", "none", '!=');
        testExpected("getComputedStyle(volumeSlider).display", "none", '==');

        // For muted video, the volume slider will hide but the mute
        // button should stay, since we always have it present for media
        // which have audio.
        run("video.muted = true");
        testExpected("getComputedStyle(muteButton).display", "none", '!=');
        testExpected("getComputedStyle(volumeSlider).display", "none", '==');

        endTest();
    });
</script>