diff -r 000000000000 -r 6474c204b198 ipc/glue/CrossProcessMutex.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ipc/glue/CrossProcessMutex.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,113 @@
+/* -*- Mode: C++; tab-width: 8; 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_CrossProcessMutex_h
+#define mozilla_CrossProcessMutex_h
+
+#include "base/process.h"
+#include "mozilla/Mutex.h"
+
+#if defined(OS_LINUX)
+#include <pthread.h>
+#include "SharedMemoryBasic.h"
+#include "mozilla/Atomics.h"
+#endif
+
+namespace IPC {
+template<typename T>
+struct ParamTraits;
+}
+
+//
+// Provides:
+//
+//  - CrossProcessMutex, a non-recursive mutex that can be shared across processes
+//  - CrossProcessMutexAutoLock, an RAII class for ensuring that Mutexes are
+//    properly locked and unlocked
+//
+// Using CrossProcessMutexAutoLock/CrossProcessMutexAutoUnlock is MUCH
+// preferred to making bare calls to CrossProcessMutex.Lock and Unlock.
+//
+namespace mozilla {
+#ifdef XP_WIN
+typedef HANDLE CrossProcessMutexHandle;
+#elif defined(OS_LINUX)
+typedef mozilla::ipc::SharedMemoryBasic::Handle CrossProcessMutexHandle;
+#else
+// Stub for other platforms. We can't use uintptr_t here since different
+// processes could disagree on its size.
+typedef uintptr_t CrossProcessMutexHandle;
+#endif
+
+class NS_COM_GLUE CrossProcessMutex
+{
+public:
+  /**
+   * CrossProcessMutex
+   * @param name A name which can reference this lock (currently unused)
+   **/
+  CrossProcessMutex(const char* aName);
+  /**
+   * CrossProcessMutex
+   * @param handle A handle of an existing cross process mutex that can be
+   *               opened.
+   */
+  CrossProcessMutex(CrossProcessMutexHandle aHandle);
+
+  /**
+   * ~CrossProcessMutex
+   **/
+  ~CrossProcessMutex();
+
+  /**
+   * Lock
+   * This will lock the mutex. Any other thread in any other process that
+   * has access to this mutex calling lock will block execution until the
+   * initial caller of lock has made a call to Unlock.
+   *
+   * If the owning process is terminated unexpectedly the mutex will be
+   * released.
+   **/
+  void Lock();
+
+  /**
+   * Unlock
+   * This will unlock the mutex. A single thread currently waiting on a lock
+   * call will resume execution and aquire ownership of the lock. No
+   * guarantees are made as to the order in which waiting threads will resume
+   * execution.
+   **/
+  void Unlock();
+
+  /**
+   * ShareToProcess
+   * This function is called to generate a serializable structure that can
+   * be sent to the specified process and opened on the other side.
+   *
+   * @returns A handle that can be shared to another process
+   */
+  CrossProcessMutexHandle ShareToProcess(base::ProcessHandle aTarget);
+
+private:
+  friend struct IPC::ParamTraits<CrossProcessMutex>;
+
+  CrossProcessMutex();
+  CrossProcessMutex(const CrossProcessMutex&);
+  CrossProcessMutex &operator=(const CrossProcessMutex&);
+
+#ifdef XP_WIN
+  HANDLE mMutex;
+#elif defined(OS_LINUX)
+  mozilla::ipc::SharedMemoryBasic* mSharedBuffer;
+  pthread_mutex_t* mMutex;
+  mozilla::Atomic<int32_t>* mCount;
+#endif
+};
+
+typedef BaseAutoLock<CrossProcessMutex> CrossProcessMutexAutoLock;
+typedef BaseAutoUnlock<CrossProcessMutex> CrossProcessMutexAutoUnlock;
+
+}
+#endif