mac: Fix StoreFunctionsForAllZones and ReplaceFunctionsForStoredZones.

base/allocator/allocator_interception_mac.mm

Index: base/allocator/allocator_interception_mac.mm
diff --git a/base/allocator/allocator_interception_mac.mm b/base/allocator/allocator_interception_mac.mm
index c484830da5e2538904cd1b8218ca8fb97e354536..fc811501cbba8f1dcde4b11dda7e3432d144afaf 100644
--- a/base/allocator/allocator_interception_mac.mm
+++ b/base/allocator/allocator_interception_mac.mm
@@ -352,9 +352,21 @@ void StoreFunctionsForAllZones() {
     ChromeMallocZone* zone = reinterpret_cast<ChromeMallocZone*>(zones[i]);
     StoreMallocZone(zone);
   }
+
+  // This ensures that the purgeable zone is at the back of the array.
+  ChromeMallocZone* purgeable_zone =
+      reinterpret_cast<ChromeMallocZone*>(malloc_default_purgeable_zone());
+  StoreMallocZone(purgeable_zone);
 }
 
 void ReplaceFunctionsForStoredZones(const MallocZoneFunctions* functions) {
+  ChromeMallocZone* default_zone =
+      reinterpret_cast<ChromeMallocZone*>(malloc_default_zone());
+  if (IsMallocZoneAlreadyStored(default_zone) &&
+      default_zone->malloc != functions->malloc) {
+    ReplaceZoneFunctions(default_zone, functions);
+  }
+
   vm_address_t* zones;
   unsigned int count;
   kern_return_t kr =
@@ -367,6 +379,14 @@ void ReplaceFunctionsForStoredZones(const MallocZoneFunctions* functions) {
       ReplaceZoneFunctions(zone, functions);
     }
   }
+
+  ChromeMallocZone* purgeable_zone =
+      reinterpret_cast<ChromeMallocZone*>(malloc_default_purgeable_zone());
+  if (IsMallocZoneAlreadyStored(purgeable_zone) &&
+      purgeable_zone->malloc != functions->malloc) {
+    ReplaceZoneFunctions(purgeable_zone, functions);
+  }
+
   g_replaced_default_zone = true;
 }