diff -r 000000000000 -r 6474c204b198 widget/windows/TaskbarPreview.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/widget/windows/TaskbarPreview.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,103 @@
+/* vim: se cin sw=2 ts=2 et : */
+/* -*- 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_widget_TaskbarPreview_h__
+#define __mozilla_widget_TaskbarPreview_h__
+
+#include <windows.h>
+#include <shobjidl.h>
+#undef LogSeverity // SetupAPI.h #defines this as DWORD
+
+#include <nsITaskbarPreview.h>
+#include <nsAutoPtr.h>
+#include <nsString.h>
+#include <nsWeakPtr.h>
+#include <nsIDocShell.h>
+#include "WindowHook.h"
+
+namespace mozilla {
+namespace widget {
+
+class TaskbarPreview : public nsITaskbarPreview
+{
+public:
+  TaskbarPreview(ITaskbarList4 *aTaskbar, nsITaskbarPreviewController *aController, HWND aHWND, nsIDocShell *aShell);
+  virtual ~TaskbarPreview();
+
+  NS_DECL_NSITASKBARPREVIEW
+
+protected:
+  // Called to update ITaskbarList4 dependent properties
+  virtual nsresult UpdateTaskbarProperties();
+
+  // Invoked when the preview is made visible
+  virtual nsresult Enable();
+  // Invoked when the preview is made invisible
+  virtual nsresult Disable();
+
+  // Detaches this preview from the nsWindow instance it's tied to
+  virtual void DetachFromNSWindow();
+
+  // Determines if the window is available and a destroy has not yet started
+  bool IsWindowAvailable() const;
+
+  // Marks this preview as being active
+  virtual nsresult ShowActive(bool active) = 0;
+  // Gets a reference to the window used to handle the preview messages
+  virtual HWND& PreviewWindow() = 0;
+
+  // Window procedure for the PreviewWindow (hooked for window previews)
+  virtual LRESULT WndProc(UINT nMsg, WPARAM wParam, LPARAM lParam);
+
+  // Returns whether or not the taskbar icon has been created for mWnd The
+  // ITaskbarList4 API requires that we wait until the icon has been created
+  // before we can call its methods.
+  bool CanMakeTaskbarCalls();
+
+  // Gets the WindowHook for the nsWindow
+  WindowHook &GetWindowHook();
+
+  // Enables/disables custom drawing for the given window
+  static void EnableCustomDrawing(HWND aHWND, bool aEnable);
+
+  // MSCOM Taskbar interface
+  nsRefPtr<ITaskbarList4> mTaskbar;
+  // Controller for this preview
+  nsCOMPtr<nsITaskbarPreviewController> mController;
+  // The HWND to the nsWindow that this object previews
+  HWND                    mWnd;
+  // Whether or not this preview is visible
+  bool                    mVisible;
+
+private:
+  // Called when the tooltip should be updated
+  nsresult UpdateTooltip();
+
+  // Requests the controller to draw into a canvas of the given width and
+  // height. The resulting bitmap is sent to the DWM to display.
+  void DrawBitmap(uint32_t width, uint32_t height, bool isPreview);
+
+  // WindowHook procedure for hooking mWnd
+  static bool MainWindowHook(void *aContext,
+                               HWND hWnd, UINT nMsg,
+                               WPARAM wParam, LPARAM lParam,
+                               LRESULT *aResult);
+
+  // Docshell corresponding to the <window> the nsWindow contains
+  nsWeakPtr               mDocShell;
+  nsString                mTooltip;
+
+  // The preview currently marked as active in the taskbar. nullptr if no
+  // preview is active (some other window is).
+  static TaskbarPreview  *sActivePreview;
+};
+
+} // namespace widget
+} // namespace mozilla
+
+#endif /* __mozilla_widget_TaskbarPreview_h__ */
+