diff -r 000000000000 -r 6474c204b198 gfx/layers/apz/util/ActiveElementManager.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gfx/layers/apz/util/ActiveElementManager.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,85 @@
+/* -*- 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"
+
+class inIDOMUtils;
+class nsIDOMEventTarget;
+class nsIDOMElement;
+class CancelableTask;
+
+namespace mozilla {
+namespace layers {
+
+/**
+ * Manages setting and clearing the ':active' CSS pseudostate in the presence
+ * of touch input.
+ */
+class ActiveElementManager {
+public:
+  NS_INLINE_DECL_REFCOUNTING(ActiveElementManager)
+
+  ActiveElementManager();
+  ~ActiveElementManager();
+
+  /**
+   * Specify the target of a touch. Typically this should be called right
+   * before HandleTouchStart(), but we give callers the flexibility to specify
+   * the target later if they don't know it at the time they call
+   * HandleTouchStart().
+   * |aTarget| may be nullptr.
+   */
+  void SetTargetElement(nsIDOMEventTarget* aTarget);
+  /**
+   * Handle a touch-start event.
+   * @param aCanBePan whether the touch can be a pan
+   */
+  void HandleTouchStart(bool aCanBePan);
+  /**
+   * Handle the start of panning.
+   */
+  void HandlePanStart();
+  /**
+   * Handle a touch-end or touch-cancel event.
+   * @param aWasClick whether the touch was a click
+   */
+  void HandleTouchEnd(bool aWasClick);
+private:
+  nsCOMPtr<inIDOMUtils> mDomUtils;
+  /**
+   * The target of the first touch point in the current touch block.
+   */
+  nsCOMPtr<nsIDOMElement> 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.
+   */
+  CancelableTask* mSetActiveTask;
+
+  // Helpers
+  void TriggerElementActivation();
+  void SetActive(nsIDOMElement* aTarget);
+  void ResetActive();
+  void SetActiveTask(nsIDOMElement* aTarget);
+  void CancelTask();
+};
+
+}
+}
+
+#endif /* mozilla_layers_ActiveElementManager_h */