mac: Hook up allocator shim.

base/allocator/allocator_shim.h

Index: base/allocator/allocator_shim.h
diff --git a/base/allocator/allocator_shim.h b/base/allocator/allocator_shim.h
index 8fd060fca6aaeee76a74cdd613af09579a56b77d..27697386eb6d1d7e75a7c08f3825b2f9ab5c17db 100644
--- a/base/allocator/allocator_shim.h
+++ b/base/allocator/allocator_shim.h
@@ -62,6 +62,13 @@ struct AllocatorDispatch {
   // allocation. If no good estimate is possible, returns zero.
   using GetSizeEstimateFn = size_t(const AllocatorDispatch* self,
                                    void* address);
+  using BatchMallocFn = unsigned(const AllocatorDispatch* self,

[DmitrySkiba, 2017/01/10 21:48:34]

We should also add a callback for free_definite_size, which is now just calls
free, which I suspect slightly regresses performance (because free has to find
allocation size again).

Also, how about somehow marking that these are macOS specific? Maybe #ifdef them
out on other platforms?

+                                 size_t size,
+                                 void** results,
+                                 unsigned num_requested);
+  using BatchFreeFn = void(const AllocatorDispatch* self,
+                           void** to_be_freed,
+                           unsigned num_to_be_freed);
 
   AllocFn* const alloc_function;
   AllocZeroInitializedFn* const alloc_zero_initialized_function;
@@ -69,6 +76,8 @@ struct AllocatorDispatch {
   ReallocFn* const realloc_function;
   FreeFn* const free_function;
   GetSizeEstimateFn* const get_size_estimate_function;
+  BatchMallocFn* const batch_malloc_function;
+  BatchFreeFn* const batch_free_function;
 
   const AllocatorDispatch* next;