diff -r 000000000000 -r 6474c204b198 gfx/layers/d3d10/ReadbackManagerD3D10.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gfx/layers/d3d10/ReadbackManagerD3D10.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,75 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * 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 GFX_READBACKMANAGERD3D10_H
+#define GFX_READBACKMANAGERD3D10_H
+
+#include <windows.h>
+#include <d3d10_1.h>
+
+#include "nsTArray.h"
+#include "nsAutoPtr.h"
+#include "gfxPoint.h"
+
+namespace mozilla {
+namespace layers {
+
+DWORD WINAPI StartTaskThread(void *aManager);
+
+struct ReadbackTask;
+
+class ReadbackManagerD3D10 MOZ_FINAL : public IUnknown
+{
+public:
+  ReadbackManagerD3D10();
+  ~ReadbackManagerD3D10();
+
+  /**
+   * Tell the readback manager to post a readback task.
+   *
+   * @param aTexture D3D10_USAGE_STAGING texture that will contain the data that
+   *                 was readback.
+   * @param aUpdate  ReadbackProcessor::Update object. This is a void pointer
+   *                 since we cannot forward declare a nested class, and do not
+   *                 export ReadbackProcessor.h
+   * @param aOrigin  Origin of the aTexture surface in the ThebesLayer
+   *                 coordinate system.
+   */
+  void PostTask(ID3D10Texture2D *aTexture, void *aUpdate, const gfxPoint &aOrigin);
+
+  virtual HRESULT STDMETHODCALLTYPE QueryInterface(REFIID riid,
+                                                   void **ppvObject);
+  virtual ULONG STDMETHODCALLTYPE AddRef(void);
+  virtual ULONG STDMETHODCALLTYPE Release(void);
+
+private:
+  friend DWORD WINAPI StartTaskThread(void *aManager);
+
+  void ProcessTasks();
+
+  // The invariant maintained by |mTaskSemaphore| is that the readback thread
+  // will awaken from WaitForMultipleObjects() at least once per readback 
+  // task enqueued by the main thread.  Since the readback thread processes
+  // exactly one task per wakeup (with one exception), no tasks are lost.  The
+  // exception is when the readback thread is shut down, which orphans the
+  // remaining tasks, on purpose.
+  HANDLE mTaskSemaphore;
+  // Event signaled when the task thread should shutdown
+  HANDLE mShutdownEvent;
+  // Handle to the task thread
+  HANDLE mTaskThread;
+
+  // FiFo list of readback tasks that are to be executed. Access is synchronized
+  // by mTaskMutex.
+  CRITICAL_SECTION mTaskMutex;
+  nsTArray<nsAutoPtr<ReadbackTask>> mPendingReadbackTasks;
+
+  ULONG mRefCnt;
+};
+
+}
+}
+
+#endif /* GFX_READBACKMANAGERD3D10_H */