Hook up allocator shim on mac.

base/trace_event/malloc_dump_provider.cc

Index: base/trace_event/malloc_dump_provider.cc
diff --git a/base/trace_event/malloc_dump_provider.cc b/base/trace_event/malloc_dump_provider.cc
index 4683694d6bb60dc15a59b544dcadf639a7464e84..c2ad9f4ed5f64d385e35d3b72bf036c8d55203ac 100644
--- a/base/trace_event/malloc_dump_provider.cc
+++ b/base/trace_event/malloc_dump_provider.cc
@@ -82,6 +82,31 @@ size_t HookGetSizeEstimate(const AllocatorDispatch* self, void* address) {
   return next->get_size_estimate_function(next, address);
 }
 
+unsigned HookBatchMalloc(const AllocatorDispatch* self,
+                         size_t size,
+                         void** results,
+                         unsigned num_requested) {
+  const AllocatorDispatch* const next = self->next;
+  unsigned count =
+      next->batch_malloc_function(next, size, results, num_requested);
+  for (unsigned i = 0; i < count; ++i) {
+    MallocDumpProvider::GetInstance()->InsertAllocation(results[i], size);
+  }
+  return count;
+}
+
+void HookBatchFree(const AllocatorDispatch* self,
+                   void** to_be_freed,
+                   unsigned num_to_be_freed) {
+  const AllocatorDispatch* const next = self->next;
+  for (unsigned i = 0; i < num_to_be_freed; ++i) {
+    if (to_be_freed[i] != nullptr) {

[Primiano Tucci (use gerrit), 2017/01/28 05:10:02]

do you know if this will actually happen frequenty or not?
The code of MallocDumpProvider can already tolerate RemoveAllocation(nullptr).
it is not super-smart about it (it will still take the lock and attempt a
hashtable lookup) but won't crash.
So if this is just for paranoid cases, you can avoid this extra check here.

[erikchen, 2017/01/31 02:21:22]

*shrug*, okay. I was just mirroring the format of HookFree.

+      MallocDumpProvider::GetInstance()->RemoveAllocation(to_be_freed[i]);
+    }
+  }
+  next->batch_free_function(next, to_be_freed, num_to_be_freed);
+}
+
 AllocatorDispatch g_allocator_hooks = {
     &HookAlloc,           /* alloc_function */
     &HookZeroInitAlloc,   /* alloc_zero_initialized_function */
@@ -89,6 +114,8 @@ AllocatorDispatch g_allocator_hooks = {
     &HookRealloc,         /* realloc_function */
     &HookFree,            /* free_function */
     &HookGetSizeEstimate, /* get_size_estimate_function */
+    &HookBatchMalloc,     /* get_size_estimate_function */
+    &HookBatchFree,       /* get_size_estimate_function */
     nullptr,              /* next */
 };
 #endif  // BUILDFLAG(USE_EXPERIMENTAL_ALLOCATOR_SHIM)