[tracing] Optimize AllocationRegister and increase max backtrace depth.

base/trace_event/heap_profiler_allocation_register_posix.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/heap_profiler_allocation_register.h"
 
 #include <stddef.h>
 #include <sys/mman.h>
 #include <unistd.h>
 
 #include "base/bits.h"
 #include "base/logging.h"
 #include "base/process/process_metrics.h"
 
 #ifndef MAP_ANONYMOUS
 #define MAP_ANONYMOUS MAP_ANON
 #endif
 
 namespace base {
 namespace trace_event {
+namespace internal {
 
 namespace {
 size_t GetGuardSize() {
   return GetPageSize();
 }
 }
 
-// static
-void* AllocationRegister::AllocateVirtualMemory(size_t size) {
+void* AllocateGuardedVirtualMemory(size_t size) {
   size = bits::Align(size, GetPageSize());
 
   // Add space for a guard page at the end.
   size_t map_size = size + GetGuardSize();
 
   void* addr = mmap(nullptr, map_size, PROT_READ | PROT_WRITE,
                     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 
   PCHECK(addr != MAP_FAILED);
 
   // Mark the last page of the allocated address space as inaccessible
   // (PROT_NONE). The read/write accessible space is still at least |min_size|
   // bytes.
   void* guard_addr =
       reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(addr) + size);
   int result = mprotect(guard_addr, GetGuardSize(), PROT_NONE);
   PCHECK(result == 0);
 
   return addr;
 }
 
-// static
-void AllocationRegister::FreeVirtualMemory(void* address,
-                                           size_t allocated_size) {
+void FreeGuardedVirtualMemory(void* address, size_t allocated_size) {
   size_t size = bits::Align(allocated_size, GetPageSize()) + GetGuardSize();
   munmap(address, size);
 }
 
+}  // namespace internal
 }  // namespace trace_event
 }  // namespace base