[Exposed=Nobody]
interface Internals {

    undefined signalTestIsDone(DOMString text);
    undefined setTestTimeout(double milliseconds);
    undefined loadReferenceTestMetadata();

    DOMString setTimeZone(DOMString timeZone);

    undefined gc();
    Promise<undefined> gcAsync();
    // Clears a named environment binding and forces its current cell to be treated as garbage.
    // This does not work for values stored only in optimized locals or registers.
    undefined markAsGarbage(DOMString variableName);
    object hitTest(double x, double y);

    const unsigned short MOD_NONE = 0;
    const unsigned short MOD_ALT = 1;
    const unsigned short MOD_CTRL = 2;
    const unsigned short MOD_SHIFT = 4;
    const unsigned short MOD_SUPER = 8;
    const unsigned short MOD_KEYPAD = 16;

    const unsigned short BUTTON_LEFT = 0;
    const unsigned short BUTTON_MIDDLE = 1;
    const unsigned short BUTTON_RIGHT = 2;

    undefined sendText(HTMLElement target, DOMString text, optional unsigned short modifiers = 0);
    undefined sendKey(HTMLElement target, DOMString keyName, optional unsigned short modifiers = 0);
    undefined paste(HTMLElement target, Utf16DOMString text);
    undefined commitText();

    // Low-level mouse primitives
    undefined mouseDown(double x, double y, optional unsigned short clickCount = 1, optional unsigned short button = 0, optional unsigned short modifiers = 0);
    undefined mouseUp(double x, double y, optional unsigned short button = 0, optional unsigned short modifiers = 0);
    undefined mouseMove(double x, double y, optional unsigned short modifiers = 0);
    undefined mouseLeave();

    // High-level mouse conveniences
    undefined click(double x, double y, optional unsigned short clickCount = 1, optional unsigned short button = 0, optional unsigned short modifiers = 0);
    undefined clickAndHold(double x, double y, optional unsigned short clickCount = 1, optional unsigned short button = 0, optional unsigned short modifiers = 0);
    Promise<undefined> wheel(double x, double y, double deltaX, double deltaY);
    undefined pinch(double x, double y, double scaleDelta, optional unsigned short modifiers = 0);

    DOMString currentCursor();

    // Returns the text that would be placed on the clipboard if the user copied the current selection now.
    // Excludes nodes whose used value of user-select is 'none' — mirroring what browsers actually copy.
    DOMString selectedTextForClipboard();

    // Drive marked/preedit-text composition via the same path platform input methods use. setMarkedTextFromInputMethod
    // updates the inline preedit — replacing any previous preedit. commitText finalizes the composition with the given
    // text. unmarkText finalizes the composition — leaving the current preedit in place. Each fires an InputEvent with
    // inputType = "insertText" on the focused editable. All are no-ops if nothing editable is focused.
    undefined setMarkedTextFromInputMethod(Utf16DOMString text);
    undefined commitTextFromInputMethod(Utf16DOMString text);
    undefined unmarkTextFromInputMethod();

    // Returns the bounds of the current text caret in viewport-relative CSS pixels — or null if no editable element is
    // focused. Used for verifying the data the platform UI feeds into IME overlay positioning.
    DOMRect? currentCaretRect();

    boolean dispatchUserActivatedEvent(EventTarget target, Event event);
    undefined spoofCurrentURL(USVString url);

    // Loads a URL in the top-level traversable — deferred so it starts outside the calling task and can land between
    // session-history traversal-queue steps, as can one requested by ConnectionFromClient::load_url in the UI process.
    undefined loadURL(USVString url);

    InternalAnimationTimeline createInternalAnimationTimeline();

    undefined simulateDragStart(double x, double y, DOMString mimeType, DOMString contents);
    undefined simulateDragMove(double x, double y);
    undefined simulateDrop(double x, double y);

    undefined expireCookiesWithTimeOffset(long long seconds);
    Promise<undefined> deleteAllCookies();

    boolean setHttpMemoryCacheEnabled(boolean enabled);
    undefined setContentBlockers(DOMString patterns);
    undefined setContentBlockingEnabled(boolean enabled);
    undefined setAutoplayPolicy(DOMString policy);

    DOMString getComputedRole(Element element);
    DOMString getComputedLabel(Element element);
    DOMString getComputedAriaLevel(Element element);
    unsigned short getEchoServerPort();

    undefined setHSTSPolicy(DOMString domain, unsigned long long maxAge, boolean includeSubDomains);
    undefined ingestHSTSHeader(USVString url, DOMString headerValue);
    boolean isKnownHSTSHost(DOMString domain);

    undefined setBrowserZoom(double factor);
    undefined setDevicePixelRatio(double ratio);

    readonly attribute boolean headless;

    DOMString dumpDisplayList();
    DOMString dumpAccessibilityTree();
    DOMString dumpLayoutTree(Node node);
    DOMString dumpPaintableTree(Node node);
    DOMString dumpStackingContextTree();
    DOMString dumpGCGraph();
    DOMString dumpSessionHistory();
    DOMString dumpUIProcessSessionHistory();
    Promise<undefined> flushSessionHistoryTraversalQueue();

    // Test-only: deterministically reproduce the navigation-vs-traversal race in Navigable::begin_navigation by
    // re-stamping the next navigation's ongoing navigation with a traversal during its unload check.
    undefined clobberNextNavigationWithATraversal();

    // Returns the shadow root of the element, if it has one, even if it's not normally accessible to JS.
    ShadowRoot? getShadowRoot(Element element);

    undefined handleSDLInputEvents();

    undefined setEnvironmentsTopLevelURL(USVString url);

    InternalGamepad connectVirtualGamepad();

    undefined setHighlightedNode(Node? node);

    undefined clearElement(HTMLElement element);

    // Returns a snapshot of the style-invalidation and recomputation counters for the current document.
    // Keys include hasAncestorWalkInvocations, hasInvalidationRuleCacheBuilds,
    // styleInvalidations, elementStyleRecomputations, and elementStyleNoopRecomputations.
    object getStyleInvalidationCounters();
    undefined resetStyleInvalidationCounters();
    // Flushes pending style work without forcing layout.
    undefined updateStyle();
    undefined setPreferredColorScheme(DOMString colorScheme);
    DOMString canvasColorScheme();
    // Returns the selector-insight cache state for stylesheet invalidation tests.
    boolean styleSheetMayHaveHasSelectors(CSSStyleSheet sheet);
    object imageAnimationStateForURL(USVString url);

    object asyncScrollingState();
    boolean asyncScrollingStateBlocksWheelEventAt(double x, double y);
    boolean asyncScrollingStateCanWheelScrollAt(double x, double y, double deltaX, double deltaY, optional boolean forceStaleWheelEventRegions = false);
    DOMString asyncScrollingStateWheelRoutingAdmission();
    DOMString asyncScrollingStateWheelScrollAdmissionAt(double x, double y, double deltaX, double deltaY, optional boolean forceStaleWheelEventRegions = false);
    DOMString asyncScrollingStateWheelTargetAt(double x, double y, double deltaX, double deltaY);

};