Properly create zero-initialized local memory.

base/metrics/persistent_memory_allocator.h

Index: base/metrics/persistent_memory_allocator.h
diff --git a/base/metrics/persistent_memory_allocator.h b/base/metrics/persistent_memory_allocator.h
index e1c85904b2168351e5d981acd9a22fe22b8218d4..311da794eede31f06a78a0183667ee2d72b5a118 100644
--- a/base/metrics/persistent_memory_allocator.h
+++ b/base/metrics/persistent_memory_allocator.h
@@ -354,6 +354,14 @@ class BASE_EXPORT LocalPersistentMemoryAllocator
   ~LocalPersistentMemoryAllocator() override;
 
  private:
+  // Allocates a block of local memory of the specified |size|, ensuring that
+  // the memory will not be physically allocated until accessed and will read
+  // as zero when that happens.
+  static void* AllocateLocalMemory(size_t size);
+
+  // Deallocates a block of local |memory| of the specified |size|.
+  static void DeallocateLocalMemory(void* memory, size_t size);
+
   DISALLOW_COPY_AND_ASSIGN(LocalPersistentMemoryAllocator);
 };