[DoNotSubmit] Added peak_memory_size to accounting-allocator.

src/base/accounting-allocator.h

Index: src/base/accounting-allocator.h
diff --git a/src/base/accounting-allocator.h b/src/base/accounting-allocator.h
index ce67f3790ef846a02f09b12101cfbf9fbcd29f59..1f26529b097af4fab2bc644f0f0be05f45b9b102 100644
--- a/src/base/accounting-allocator.h
+++ b/src/base/accounting-allocator.h
@@ -5,6 +5,7 @@
 #ifndef V8_BASE_ACCOUNTING_ALLOCATOR_H_
 #define V8_BASE_ACCOUNTING_ALLOCATOR_H_
 
+#include "src/base/platform/mutex.h"
 #include "src/base/atomicops.h"
 #include "src/base/macros.h"
 
@@ -13,17 +14,20 @@ namespace base {
 
 class AccountingAllocator final {
  public:
-  AccountingAllocator() = default;
-  ~AccountingAllocator() = default;
+  AccountingAllocator() {}
+  ~AccountingAllocator() {}
 
   // Returns nullptr on failed allocation.
   void* Allocate(size_t bytes);
   void Free(void* memory, size_t bytes);
 
   size_t GetCurrentMemoryUsage() const;
+  size_t GetPeakMemoryUsage() const;
 
  private:
-  AtomicWord current_memory_usage_ = 0;
+  size_t current_memory_usage_ = 0;
+  size_t peak_memory_usage_ = 0;
+  Mutex mutex_;
 
   DISALLOW_COPY_AND_ASSIGN(AccountingAllocator);
 };