Track JS allocations as they arrive with no affection on performance when tracking is switched off

src/serialize.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 348 matching lines @@
   void ReadChunk(
       Object** start, Object** end, int space, Address object_address);
   void ReadObject(int space_number, Object** write_back);
 
   // This routine both allocates a new object, and also keeps
   // track of where objects have been allocated so that we can
   // fix back references when deserializing.
   Address Allocate(int space_index, int size) {
     Address address = high_water_[space_index];
     high_water_[space_index] = address + size;
+    HeapProfiler* profiler = isolate_->heap_profiler();
+    if (profiler->is_tracking_allocations()) {
+      profiler->NewObjectEvent(address, size);
+    }
     return address;
   }
 
   // This returns the address of an object that has been described in the
   // snapshot as being offset bytes back in a particular space.
   HeapObject* GetAddressFromEnd(int space) {
     int offset = source_->GetInt();
     offset <<= kObjectAlignmentBits;
     return HeapObject::FromAddress(high_water_[space] - offset);
   }
@@ skipping 276 matching lines @@
  private:
   virtual bool ShouldBeInThePartialSnapshotCache(HeapObject* o) {
     return false;
   }
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_SERIALIZE_H_