Support text track selection in video controls

LayoutTests/media/media-controls.js

 var captionsButtonElement;
 var captionsButtonCoordinates;
 
 // As specified in mediaControls.css, this is how long it takes to fade out controls
 const controlsFadeOutDurationMs = 300;
 
 // The timeout for the hide-after-no-mouse-movement behavior. Defined (and
 // should mirror) the value 'timeWithoutMouseMovementBeforeHidingMediaControls'
 // in MediaControls.cpp.
 const controlsMouseMovementTimeoutMs = 3000;
@@ skipping 29 matching lines @@
 
 function mediaControlsButton(element, id)
 {
     var controlID = "-webkit-media-controls-" + id;
     var button = mediaControlsElement(internals.shadowRoot(element).firstChild, controlID);
     if (!button)
         throw "Failed to find media control element ID '" + id + "'";
     return button;
 }
 
+function elementCoordinates(element)
+{
+    var elementBoundingRect = element.getBoundingClientRect();
+    var x = elementBoundingRect.left + elementBoundingRect.width / 2;
+    var y = elementBoundingRect.top + elementBoundingRect.height / 2;
+    return new Array(x, y);
+}
+
 function mediaControlsButtonCoordinates(element, id)
 {
     var button = mediaControlsButton(element, id);
-    var buttonBoundingRect = button.getBoundingClientRect();
-    var x = buttonBoundingRect.left + buttonBoundingRect.width / 2;
-    var y = buttonBoundingRect.top + buttonBoundingRect.height / 2;
-    return new Array(x, y);
+    return elementCoordinates(button);
 }
 
 function mediaControlsButtonDimensions(element, id)
 {
     var button = mediaControlsButton(element, id);
     var buttonBoundingRect = button.getBoundingClientRect();
     return new Array(buttonBoundingRect.width, buttonBoundingRect.height);
 }
 
 function textTrackDisplayElement(parentElement, id, cueNumber)
@@ skipping 45 matching lines @@
         testExpected("captionsButtonCoordinates[0]", 0, ">");
         testExpected("captionsButtonCoordinates[1]", 0, ">");
         testExpected("captionsButtonElement.disabled", false);
     } else {
         consoleWrite("** Caption button should not be visible.");
         testExpected("captionsButtonCoordinates[0]", 0, "<=");
         testExpected("captionsButtonCoordinates[1]", 0, "<=");
     }
 }
 
+function clickAtCoordinates(x, y)
+{
+    eventSender.mouseMoveTo(x, y);
+    eventSender.mouseDown();
+    eventSender.mouseUp();
+}
+
 function clickCCButton()
 {
     consoleWrite("*** Click the CC button.");
-    eventSender.mouseMoveTo(captionsButtonCoordinates[0], captionsButtonCoordinates[1]);
-    eventSender.mouseDown();
-    eventSender.mouseUp();
+    clickAtCoordinates(captionsButtonCoordinates[0], captionsButtonCoordinates[1]);
+}
+
+function textTrackListItem(video, index)
+{
+    var textTrackListElementID = "-internal-media-controls-text-track-list";
+    var textTrackListElement = mediaControlsElement(internals.shadowRoot(video).firstChild, textTrackListElementID);
+    if (!textTrackListElement)
+        throw "Failed to find text track list element";
+
+    var tracksSectionElement = textTrackListElement.lastChild;
+    var trackListItems = tracksSectionElement.childNodes;
+    for (var i = 0; i < trackListItems.length; i++) {
+        var trackListItem = trackListItems[i];
+        if (trackListItem.firstChild.getAttribute("data-webkit-track-index") == index)
+            return trackListItem;
+    }
+}
+
+function selectTextTrack(video, index)
+{
+    clickCCButton();
+    var trackListItemElement = textTrackListItem(video, index);
+    var trackListItemCoordinates = elementCoordinates(trackListItemElement);
+    clickAtCoordinates(trackListItemCoordinates[0], trackListItemCoordinates[1]);
+}
+
+function turnClosedCaptionsOff(video)
+{
+    selectTextTrack(video, -1);
 }
 
 function runAfterHideMediaControlsTimerFired(func, mediaElement)
 {
     if (mediaElement.paused)
         throw "The media element is not playing";
 
     // Compute the time it'll take until the controls will be invisible -
     // assuming playback has been started prior to invoking this
     // function. Allow 500ms slack.
     var hideTimeoutMs = controlsMouseMovementTimeoutMs + controlsFadeOutDurationMs + 500;
 
     if (!mediaElement.loop && hideTimeoutMs >= 1000 * (mediaElement.duration - mediaElement.currentTime))
         throw "The media will end before the controls have been hidden";
 
     setTimeout(func, hideTimeoutMs);
 }