[Tracing] Add allocation register for heap profiling

base/trace_event/memory_profiler_allocation_register_win.cc

+// Copyright 2015 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/trace_event/memory_profiler_allocation_register.h"
+
+#include <windows.h>
+
+#include "base/bits.h"
+#include "base/logging.h"
+#include "base/process/process_metrics.h"
+
+namespace base {
+namespace trace_event {
+
+// static
+void* AllocationRegister::AllocateVirtualMemory(size_t min_size) {
+  size_t size = bits::Align(min_size, GetPageSize());
+
+  // Add space for a guard page at the end.
+  size_t map_size = size + GetPageSize();
+
+  // Reserve the address space. This does not make the memory usable yet.
+  void* addr = VirtualAlloc(nullptr, map_size, MEM_RESERVE, PAGE_NOACCESS);
+
+  PCHECK(addr != nullptr);
+
+  // Commit the non-guard pages as read-write memory.
+  void* result = VirtualAlloc(addr, size, MEM_COMMIT, PAGE_READWRITE);
+
+  PCHECK(result != nullptr);
+
+  // Mark the last page of the allocated address space as guard page. (NB: The
+  // |PAGE_GUARD| flag is not the flag to use here, that flag can be used to
+  // detect and intercept access to a certain memory region. Accessing a
+  // |PAGE_NOACCESS| page will raise a general protection fault.) The
+  // read/write accessible space is still at least |min_size| bytes.
+  void* guard_addr = static_cast<void*>(static_cast<uint8_t*>(addr) + size);
+  size_t guard_size = map_size - size;
+  result = VirtualAlloc(guard_addr, guard_size, MEM_COMMIT, PAGE_NOACCESS);
+  PCHECK(result != nullptr);
+
+  return addr;
+}
+
+// static
+void AllocationRegister::FreeVirtualMemory(void* address,
+                                           size_t allocated_min_size) {
+  // For |VirtualFree|, the size passed with |MEM_RELEASE| mut be 0. Windows
+  // automatically frees the entire region that was reserved by the
+  // |VirtualAlloc| with flag |MEM_RESERVE|.
+  VirtualFree(address, 0, MEM_RELEASE);
+}
+
+}  // namespace trace_event
+}  // namespace base