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diff --git a/chromium/base/mac/scoped_mach_vm.h b/chromium/base/mac/scoped_mach_vm.h
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+++ b/chromium/base/mac/scoped_mach_vm.h
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+// Copyright 2014 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.
+
+#ifndef BASE_MAC_SCOPED_MACH_VM_H_
+#define BASE_MAC_SCOPED_MACH_VM_H_
+
+#include <mach/mach.h>
+
+#include <algorithm>
+
+#include "base/base_export.h"
+#include "base/basictypes.h"
+#include "base/logging.h"
+
+// Use ScopedMachVM to supervise ownership of pages in the current process
+// through the Mach VM subsystem. Pages allocated with vm_allocate can be
+// released when exiting a scope with ScopedMachVM.
+//
+// The Mach VM subsystem operates on a page-by-page basis, and a single VM
+// allocation managed by a ScopedMachVM object may span multiple pages. As far
+// as Mach is concerned, allocated pages may be deallocated individually. This
+// is in contrast to higher-level allocators such as malloc, where the base
+// address of an allocation implies the size of an allocated block.
+// Consequently, it is not sufficient to just pass the base address of an
+// allocation to ScopedMachVM, it also needs to know the size of the
+// allocation. To avoid any confusion, both the base address and size must
+// be page-aligned.
+//
+// When dealing with Mach VM, base addresses will naturally be page-aligned,
+// but user-specified sizes may not be. If there's a concern that a size is
+// not page-aligned, use the mach_vm_round_page macro to correct it.
+//
+// Example:
+//
+//   vm_address_t address = 0;
+//   vm_size_t size = 12345;  // This requested size is not page-aligned.
+//   kern_return_t kr =
+//       vm_allocate(mach_task_self(), &address, size, VM_FLAGS_ANYWHERE);
+//   if (kr != KERN_SUCCESS) {
+//     return false;
+//   }
+//   ScopedMachVM vm_owner(address, mach_vm_round_page(size));
+
+namespace base {
+namespace mac {
+
+class BASE_EXPORT ScopedMachVM {
+ public:
+  explicit ScopedMachVM(vm_address_t address = 0, vm_size_t size = 0)
+      : address_(address),
+        size_(size) {
+    DCHECK(address % PAGE_SIZE == 0);
+    DCHECK(size % PAGE_SIZE == 0);
+  }
+
+  ~ScopedMachVM() {
+    if (size_) {
+      vm_deallocate(mach_task_self(), address_, size_);
+    }
+  }
+
+  void reset(vm_address_t address = 0, vm_size_t size = 0);
+
+  vm_address_t address() const {
+    return address_;
+  }
+
+  vm_size_t size() const {
+    return size_;
+  }
+
+  void swap(ScopedMachVM& that) {
+    std::swap(address_, that.address_);
+    std::swap(size_, that.size_);
+  }
+
+  void release() {
+    address_ = 0;
+    size_ = 0;
+  }
+
+ private:
+  vm_address_t address_;
+  vm_size_t size_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedMachVM);
+};
+
+}  // namespace mac
+}  // namespace base
+
+#endif  // BASE_MAC_SCOPED_MACH_VM_H_