[snapshot] introduce SnapshotCreator API.

src/snapshot/startup-serializer.cc

Index: src/snapshot/startup-serializer.cc
diff --git a/src/snapshot/startup-serializer.cc b/src/snapshot/startup-serializer.cc
index c71c16b1fdbae8b4eb60fc93fc48f145a596e763..9a38ceb2be32f881639f2787249431ccc6689054 100644
--- a/src/snapshot/startup-serializer.cc
+++ b/src/snapshot/startup-serializer.cc
@@ -12,9 +12,10 @@ namespace internal {
 
 StartupSerializer::StartupSerializer(
     Isolate* isolate, SnapshotByteSink* sink,
-    FunctionCodeHandling function_code_handling)
+    v8::SnapshotCreator::FunctionCodeHandling function_code_handling)
     : Serializer(isolate, sink),
-      function_code_handling_(function_code_handling),
+      clear_function_code_(function_code_handling ==
+                           v8::SnapshotCreator::FunctionCodeHandling::kClear),
       serializing_builtins_(false) {
   InitializeCodeAddressMap();
 }
@@ -27,7 +28,7 @@ void StartupSerializer::SerializeObject(HeapObject* obj, HowToCode how_to_code,
                                         WhereToPoint where_to_point, int skip) {
   DCHECK(!obj->IsJSFunction());
 
-  if (function_code_handling_ == CLEAR_FUNCTION_CODE) {
+  if (clear_function_code_) {
     if (obj->IsCode()) {
       Code* code = Code::cast(obj);
       // If the function code is compiled (either as native code or bytecode),
@@ -42,7 +43,6 @@ void StartupSerializer::SerializeObject(HeapObject* obj, HowToCode how_to_code,
       obj = isolate()->heap()->undefined_value();
     }
   } else if (obj->IsCode()) {
-    DCHECK_EQ(KEEP_FUNCTION_CODE, function_code_handling_);
     Code* code = Code::cast(obj);
     if (code->kind() == Code::FUNCTION) {
       code->ClearInlineCaches();