Introduce a Gin class instead of using global functions to control gin

gin/initialize.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/initialize.h"
-
-#include <stdlib.h>
-#include <string.h>
-
-#include "gin/array_buffer.h"
-#include "gin/per_isolate_data.h"
-
-namespace gin {
-
-namespace {
-
-bool GenerateEntropy(unsigned char* buffer, size_t amount) {
-  // TODO(abarth): Gin needs a source of entropy.
-  return false;
-}
-
-const char kFlags[] = "--use_strict --harmony";
-
-}
-
-void Initialize() {
-  v8::V8::SetArrayBufferAllocator(ArrayBufferAllocator::SharedInstance());
-  v8::V8::InitializeICU();
-  v8::V8::SetFlagsFromString(kFlags,
-      static_cast<uint32_t>(arraysize(kFlags)) - 1);
-  v8::V8::SetEntropySource(&GenerateEntropy);
-  v8::V8::Initialize();
-
-  v8::Isolate* isolate = v8::Isolate::GetCurrent();
-  v8::HandleScope handle_scope(isolate);
-  new PerIsolateData(isolate);
-}
-
-}  // namespace gin