diff -r 000000000000 -r 6474c204b198 ipc/chromium/src/base/lock_impl_win.cc
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ipc/chromium/src/base/lock_impl_win.cc	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,73 @@
+// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/lock_impl.h"
+#include "base/logging.h"
+
+// NOTE: Although windows critical sections support recursive locks, we do not
+// allow this, and we will commonly fire a DCHECK() if a thread attempts to
+// acquire the lock a second time (while already holding it).
+
+LockImpl::LockImpl() {
+#ifndef NDEBUG
+  recursion_count_shadow_ = 0;
+  recursion_used_ = false;
+  owning_thread_id_ = 0;
+#endif  // NDEBUG
+  // The second parameter is the spin count, for short-held locks it avoid the
+  // contending thread from going to sleep which helps performance greatly.
+  ::InitializeCriticalSectionAndSpinCount(&os_lock_, 2000);
+}
+
+LockImpl::~LockImpl() {
+  ::DeleteCriticalSection(&os_lock_);
+}
+
+bool LockImpl::Try() {
+  if (::TryEnterCriticalSection(&os_lock_) != FALSE) {
+#ifndef NDEBUG
+    // ONLY access data after locking.
+    owning_thread_id_ = PlatformThread::CurrentId();
+    DCHECK_NE(owning_thread_id_, 0);
+    recursion_count_shadow_++;
+    if (2 == recursion_count_shadow_ && !recursion_used_) {
+      recursion_used_ = true;
+      DCHECK(false);  // Catch accidental redundant lock acquisition.
+    }
+#endif
+    return true;
+  }
+  return false;
+}
+
+void LockImpl::Lock() {
+  ::EnterCriticalSection(&os_lock_);
+#ifndef NDEBUG
+  // ONLY access data after locking.
+  owning_thread_id_ = PlatformThread::CurrentId();
+  DCHECK_NE(owning_thread_id_, 0);
+  recursion_count_shadow_++;
+  if (2 == recursion_count_shadow_ && !recursion_used_) {
+    recursion_used_ = true;
+    DCHECK(false);  // Catch accidental redundant lock acquisition.
+  }
+#endif  // NDEBUG
+}
+
+void LockImpl::Unlock() {
+#ifndef NDEBUG
+  --recursion_count_shadow_;  // ONLY access while lock is still held.
+  DCHECK(0 <= recursion_count_shadow_);
+  owning_thread_id_ = 0;
+#endif  // NDEBUG
+  ::LeaveCriticalSection(&os_lock_);
+}
+
+// In non-debug builds, this method is declared as an empty inline method.
+#ifndef NDEBUG
+void LockImpl::AssertAcquired() const {
+  DCHECK(recursion_count_shadow_ > 0);
+  DCHECK_EQ(owning_thread_id_, PlatformThread::CurrentId());
+}
+#endif