Expose a lower bound of malloc'd memory via heap statistics

src/compiler/zone-pool.h

Index: src/compiler/zone-pool.h
diff --git a/src/compiler/zone-pool.h b/src/compiler/zone-pool.h
index aaf9daac464f7bf7e712b597587c08867d90d23d..44a649fcfb45d15c66ee971963c60fdbf5e5b283 100644
--- a/src/compiler/zone-pool.h
+++ b/src/compiler/zone-pool.h
@@ -61,7 +61,7 @@ class ZonePool final {
     DISALLOW_COPY_AND_ASSIGN(StatsScope);
   };
 
-  ZonePool();
+  explicit ZonePool(base::AccountingAllocator* allocator);
   ~ZonePool();
 
   size_t GetMaxAllocatedBytes();
@@ -82,6 +82,7 @@ class ZonePool final {
   Stats stats_;
   size_t max_allocated_bytes_;
   size_t total_deleted_bytes_;
+  base::AccountingAllocator* allocator_;
 
   DISALLOW_COPY_AND_ASSIGN(ZonePool);
 };