Track peak Zone memory usage and report it via HeapStatistics

src/base/accounting-allocator.cc

 // Copyright 2016 the V8 project 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 "src/base/accounting-allocator.h"
 
 #include <cstdlib>
 
 #if V8_LIBC_BIONIC
 #include <malloc.h>  // NOLINT
 #endif
 
 namespace v8 {
 namespace base {
 
 void* AccountingAllocator::Allocate(size_t bytes) {
   void* memory = malloc(bytes);
-  if (memory) NoBarrier_AtomicIncrement(&current_memory_usage_, bytes);
+  if (memory) {
+    AtomicWord current =
+        NoBarrier_AtomicIncrement(&current_memory_usage_, bytes);
+    AtomicWord max = NoBarrier_Load(&max_memory_usage_);
+    while (current > max) {
+      max = NoBarrier_CompareAndSwap(&max_memory_usage_, max, current);
+    }
+  }
   return memory;
 }
 
 void AccountingAllocator::Free(void* memory, size_t bytes) {
   free(memory);
   NoBarrier_AtomicIncrement(&current_memory_usage_,
                             -static_cast<AtomicWord>(bytes));
 }
 
 size_t AccountingAllocator::GetCurrentMemoryUsage() const {
   return NoBarrier_Load(&current_memory_usage_);
 }
 
+size_t AccountingAllocator::GetMaxMemoryUsage() const {
+  return NoBarrier_Load(&max_memory_usage_);
+}
+
 }  // namespace base
 }  // namespace v8