Track peak Zone memory usage and report it via HeapStatistics

src/base/accounting-allocator.cc

Index: src/base/accounting-allocator.cc
diff --git a/src/base/accounting-allocator.cc b/src/base/accounting-allocator.cc
index 2269c60680c0e1d13b542ebbc9a56451382560b5..c56f037c04c00a9e6ec97976a6b0fb614e7cd091 100644
--- a/src/base/accounting-allocator.cc
+++ b/src/base/accounting-allocator.cc
@@ -15,7 +15,14 @@ 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;
 }
 
@@ -29,5 +36,9 @@ 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