Hook up allocator shim on mac.

base/debug/thread_heap_usage_tracker.cc

Index: base/debug/thread_heap_usage_tracker.cc
diff --git a/base/debug/thread_heap_usage_tracker.cc b/base/debug/thread_heap_usage_tracker.cc
index 25af20b0aa7d20ecdfa04af0bda3d6d0ab2eb884..accd1b3ab9eb59edf43d685a6f5a5d43ad33d73a 100644
--- a/base/debug/thread_heap_usage_tracker.cc
+++ b/base/debug/thread_heap_usage_tracker.cc
@@ -130,10 +130,34 @@ size_t GetSizeEstimateFn(const AllocatorDispatch* self, void* address) {
   return self->next->get_size_estimate_function(self->next, address);
 }
 
+unsigned BatchMallocFn(const AllocatorDispatch* self,
+                       size_t size,
+                       void** results,
+                       unsigned num_requested) {
+  unsigned count = self->next->batch_malloc_function(self->next, size, results,
+                                                     num_requested);
+  for (unsigned i = 0; i < count; ++i) {
+    RecordAlloc(self->next, results[i], size);
+  }
+  return count;
+}
+
+void BatchFreeFn(const AllocatorDispatch* self,
+                 void** to_be_freed,
+                 unsigned num_to_be_freed) {
+  for (unsigned i = 0; i < num_to_be_freed; ++i) {
+    if (to_be_freed[i] != nullptr) {
+      RecordFree(self->next, to_be_freed[i]);
+    }
+  }
+  self->next->batch_free_function(self->next, to_be_freed, num_to_be_freed);
+}
+
 // The allocator dispatch used to intercept heap operations.
 AllocatorDispatch allocator_dispatch = {
     &AllocFn, &AllocZeroInitializedFn, &AllocAlignedFn, &ReallocFn,
-    &FreeFn,  &GetSizeEstimateFn,      nullptr};
+    &FreeFn,  &GetSizeEstimateFn,      &BatchMallocFn,  &BatchFreeFn,
+    nullptr};
 
 ThreadHeapUsage* GetOrCreateThreadUsage() {
   ThreadHeapUsage* allocator_usage =