Fix confusion over on-disk object id sizes during instance serialization.

runtime/vm/heap_profiler.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_HEAP_PROFILER_H_
 #define VM_HEAP_PROFILER_H_
 
 #include <set>
 
 #include "include/dart_api.h"
@@ skipping 56 matching lines @@
     kBoolean = 4,
     kChar = 5,
     kFloat = 6,
     kDouble = 7,
     kByte = 8,
     kShort = 9,
     kInt = 10,
     kLong = 11
   };
 
+  static const int kObjectIdSize = sizeof(uint64_t);  // NOLINT
+
   HeapProfiler(Dart_FileWriteCallback callback, void* stream);
   ~HeapProfiler();
 
   // Writes a root to the heap dump.
   void WriteRoot(const RawObject* raw_obj);
 
   // Writes a object to the heap dump.
   void WriteObject(const RawObject* raw_obj);
 
  private:
@@ skipping 67 matching lines @@
     void Write(const uint8_t* value, intptr_t size);
 
     // Appends an 8-, 16-, 32- or 64-bit value to the body in
     // big-endian format.
     void Write8(uint8_t value);
     void Write16(uint16_t value);
     void Write32(uint32_t value);
     void Write64(uint64_t value);
 
     // Appends an ID to the body.
-    void WritePointer(const void* value);
+    void WriteObjectId(const void* value);
 
    private:
     // A tag value that describes the record format.
     uint8_t tag_;
 
     // The payload of the record as described by the tag.
     Buffer body_;
 
     // Parent object.
     HeapProfiler* profiler_;
@@ skipping 13 matching lines @@
     void Write(const uint8_t* value, intptr_t size);
 
     // Appends an 8-, 16-, 32- or 64-bit value to the heap dump
     // record.
     void Write8(uint8_t value);
     void Write16(uint16_t value);
     void Write32(uint32_t value);
     void Write64(uint64_t value);
 
     // Appends an ID to the current heap dump record.
-    void WritePointer(const void* value);
+    void WriteObjectId(const void* value);
 
    private:
     // The record instance that receives forwarded write calls.
     Record* record_;
   };
 
   // Id canonizers.
   const RawClass* ClassId(const RawClass* raw_class);
   const RawObject* ObjectId(const RawObject* raw_obj);
   const char* StringId(const char* c_string);
@@ skipping 95 matching lines @@
   virtual void VisitObject(RawObject* obj);
 
  private:
   HeapProfiler* profiler_;
   DISALLOW_COPY_AND_ASSIGN(HeapProfilerObjectVisitor);
 };
 
 }  // namespace dart
 
 #endif  // VM_HEAP_PROFILER_H_