Refactor some of the snapshot writer classes to eliminate code duplication.

vm/dart_api_impl.cc

 // Copyright (c) 2011, 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.
 
 #include "include/dart_api.h"
 
 #include "vm/bigint_operations.h"
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
 #include "vm/dart.h"
@@ skipping 632 matching lines @@
   }
   const char* msg = CheckIsolateState(isolate,
                                       ClassFinalizer::kGeneratingSnapshot);
   if (msg != NULL) {
     return Api::Error(msg);
   }
   // Since this is only a snapshot the root library should not be set.
   isolate->object_store()->set_root_library(Library::Handle());
   SnapshotWriter writer(Snapshot::kFull, buffer, ApiAllocator);
   writer.WriteFullSnapshot();
-  *size = writer.Size();
+  *size = writer.BytesWritten();
   return Api::Success();
 }
 
 
 DART_EXPORT Dart_Handle Dart_CreateScriptSnapshot(uint8_t** buffer,
                                                   intptr_t* size) {
   Isolate* isolate = Isolate::Current();
   DARTSCOPE(isolate);
   TIMERSCOPE(time_creating_snapshot);
   if (buffer == NULL) {
     return Api::Error("%s expects argument 'buffer' to be non-null.",
                       CURRENT_FUNC);
   }
   if (size == NULL) {
     return Api::Error("%s expects argument 'size' to be non-null.",
                       CURRENT_FUNC);
   }
   const char* msg = CheckIsolateState(isolate);
   if (msg != NULL) {
     return Api::Error(msg);
   }
   Library& library = Library::Handle(isolate->object_store()->root_library());
   if (library.IsNull()) {
     return Api::Error("%s expects the isolate to have a script loaded in it.",
                       CURRENT_FUNC);
   }
   ScriptSnapshotWriter writer(buffer, ApiAllocator);
   writer.WriteScriptSnapshot(library);
-  *size = writer.Size();
+  *size = writer.BytesWritten();
   return Api::Success();
 }
 
 
 DART_EXPORT void Dart_InterruptIsolate(Dart_Isolate isolate) {
   if (isolate == NULL) {
     FATAL1("%s expects argument 'isolate' to be non-null.",  CURRENT_FUNC);
   }
   Isolate* iso = reinterpret_cast<Isolate*>(isolate);
   iso->ScheduleInterrupts(Isolate::kApiInterrupt);
@@ skipping 1842 matching lines @@
     }
     delete debug_region;
   } else {
     *buffer = NULL;
     *buffer_size = 0;
   }
 }
 
 
 }  // namespace dart