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diff --git a/gfx/layers/apz/util/ActiveElementManager.h b/gfx/layers/apz/util/ActiveElementManager.h
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+++ b/gfx/layers/apz/util/ActiveElementManager.h
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+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_layers_ActiveElementManager_h
+#define mozilla_layers_ActiveElementManager_h
+
+#include "nsCOMPtr.h"
+#include "nsISupportsImpl.h"
+
+namespace mozilla {
+
+class CancelableRunnable;
+
+namespace dom {
+class Element;
+class EventTarget;
+} // namespace dom
+
+namespace layers {
+
+/**
+ * Manages setting and clearing the ':active' CSS pseudostate in the presence
+ * of touch input.
+ */
+class ActiveElementManager {
+  ~ActiveElementManager();
+public:
+  NS_INLINE_DECL_REFCOUNTING(ActiveElementManager)
+
+  ActiveElementManager();
+
+  /**
+   * Specify the target of a touch. Typically this should be called right
+   * after HandleTouchStart(), but in cases where the APZ needs to wait for
+   * a content response the HandleTouchStart() may be delayed, in which case
+   * this function can be called first.
+   * |aTarget| may be nullptr.
+   */
+  void SetTargetElement(dom::EventTarget* aTarget);
+  /**
+   * Handle a touch-start state notification from APZ. This notification
+   * may be delayed until after touch listeners have responded to the APZ.
+   * @param aCanBePan whether the touch can be a pan
+   */
+  void HandleTouchStart(bool aCanBePan);
+  /**
+   * Clear the active element.
+   */
+  void ClearActivation();
+  /**
+   * Handle a touch-end or touch-cancel event.
+   * @param aWasClick whether the touch was a click
+   */
+  void HandleTouchEndEvent(bool aWasClick);
+  /**
+   * Handle a touch-end state notification from APZ. This notification may be
+   * delayed until after touch listeners have responded to the APZ.
+   */
+  void HandleTouchEnd();
+  /**
+   * @return true iff the currently active element (or one of its ancestors)
+   * actually had a style for the :active pseudo-class. The currently active
+   * element is the root element if no other elements are active.
+   */
+  bool ActiveElementUsesStyle() const;
+private:
+  /**
+   * The target of the first touch point in the current touch block.
+   */
+  nsCOMPtr<dom::Element> mTarget;
+  /**
+   * Whether the current touch block can be a pan. Set in HandleTouchStart().
+   */
+  bool mCanBePan;
+  /**
+   * Whether mCanBePan has been set for the current touch block.
+   * We need to keep track of this to allow HandleTouchStart() and
+   * SetTargetElement() to be called in either order.
+   */
+  bool mCanBePanSet;
+  /**
+   * A task for calling SetActive() after a timeout.
+   */
+  RefPtr<CancelableRunnable> mSetActiveTask;
+  /**
+   * See ActiveElementUsesStyle() documentation.
+   */
+  bool mActiveElementUsesStyle;
+
+  // Helpers
+  void TriggerElementActivation();
+  void SetActive(dom::Element* aTarget);
+  void ResetActive();
+  void ResetTouchBlockState();
+  void SetActiveTask(const nsCOMPtr<dom::Element>& aTarget);
+  void CancelTask();
+};
+
+} // namespace layers
+} // namespace mozilla
+
+#endif /* mozilla_layers_ActiveElementManager_h */