Remove unnecessary virtual methods in the serializer.

src/serialize.h

Index: src/serialize.h
diff --git a/src/serialize.h b/src/serialize.h
index f05a42ae2aa814b55628f42cbe0c21c70e2208f6..9e3cc88662e0b053a3c2705cf3bde11c11a49cd5 100644
--- a/src/serialize.h
+++ b/src/serialize.h
@@ -456,7 +456,6 @@ class Serializer : public SerializerDeserializer {
   static const int kInvalidRootIndex = -1;
 
   int RootIndex(HeapObject* heap_object, HowToCode from);
-  virtual bool ShouldBeInThePartialSnapshotCache(HeapObject* o) = 0;
   intptr_t root_index_wave_front() { return root_index_wave_front_; }
   void set_root_index_wave_front(intptr_t value) {
     ASSERT(value >= root_index_wave_front_);
@@ -572,15 +571,15 @@ class PartialSerializer : public Serializer {
   }
 
   // Serialize the objects reachable from a single object pointer.
-  virtual void Serialize(Object** o);
+  void Serialize(Object** o);
   virtual void SerializeObject(Object* o,
                                HowToCode how_to_code,
                                WhereToPoint where_to_point,
                                int skip);
 
- protected:
-  virtual int PartialSnapshotCacheIndex(HeapObject* o);
-  virtual bool ShouldBeInThePartialSnapshotCache(HeapObject* o) {
+ private:
+  int PartialSnapshotCacheIndex(HeapObject* o);
+  bool ShouldBeInThePartialSnapshotCache(HeapObject* o) {
     // Scripts should be referred only through shared function infos.  We can't
     // allow them to be part of the partial snapshot because they contain a
     // unique ID, and deserializing several partial snapshots containing script
@@ -593,7 +592,7 @@ class PartialSerializer : public Serializer {
                startup_serializer_->isolate()->heap()->fixed_cow_array_map();
   }
 
- private:
+
   Serializer* startup_serializer_;
   DISALLOW_COPY_AND_ASSIGN(PartialSerializer);
 };
@@ -625,11 +624,6 @@ class StartupSerializer : public Serializer {
     SerializeWeakReferences();
     Pad();
   }
-
- private:
-  virtual bool ShouldBeInThePartialSnapshotCache(HeapObject* o) {
-    return false;
-  }
 };