Move V8 snapshot loading code from isolate_holder to gin/v8_startup_data.{h,cc}.

gin/test/v8_test.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "gin/test/v8_test.h"
 
 #include "gin/array_buffer.h"
 #include "gin/public/isolate_holder.h"
-
-#ifdef V8_USE_EXTERNAL_STARTUP_DATA
-#include "gin/public/isolate_holder.h"
-#endif
+#include "gin/v8_initializer.h"
 
 using v8::Context;
 using v8::Local;
 using v8::HandleScope;
 
 namespace gin {
 
 V8Test::V8Test() {
 }
 
 V8Test::~V8Test() {
 }
 
 void V8Test::SetUp() {
 #ifdef V8_USE_EXTERNAL_STARTUP_DATA
-  gin::IsolateHolder::LoadV8Snapshot();
+  gin::V8Initializer::LoadV8Snapshot();
 #endif
-  gin::IsolateHolder::Initialize(gin::IsolateHolder::kStrictMode,
+  gin::V8Initializer::Initialize(gin::IsolateHolder::kStrictMode,
                                  gin::ArrayBufferAllocator::SharedInstance());
+
   instance_.reset(new gin::IsolateHolder);
   instance_->isolate()->Enter();
   HandleScope handle_scope(instance_->isolate());
   context_.Reset(instance_->isolate(), Context::New(instance_->isolate()));
   Local<Context>::New(instance_->isolate(), context_)->Enter();
 }
 
 void V8Test::TearDown() {
   {
     HandleScope handle_scope(instance_->isolate());
     Local<Context>::New(instance_->isolate(), context_)->Exit();
     context_.Reset();
   }
   instance_->isolate()->Exit();
   instance_.reset();
 }
 
 }  // namespace gin