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

gin/gin.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/gin.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "base/rand_util.h"
+#include "base/sys_info.h"
+#include "gin/array_buffer.h"
+#include "gin/per_isolate_data.h"
+
+namespace gin {
+
+namespace {
+
+bool GenerateEntropy(unsigned char* buffer, size_t amount) {
+  base::RandBytes(buffer, amount);
+  return true;
+}
+
+
+void EnsureV8Initialized() {
+  static bool v8_is_initialized = false;
+  if (v8_is_initialized)
+    return;
+  v8_is_initialized = true;
+
+  v8::V8::SetArrayBufferAllocator(ArrayBufferAllocator::SharedInstance());
+  static const char v8_flags[] = "--use_strict --harmony";
+  v8::V8::SetFlagsFromString(v8_flags, sizeof(v8_flags) - 1);
+  v8::V8::SetEntropySource(&GenerateEntropy);
+  v8::V8::Initialize();
+}
+
+}  // namespace
+
+Gin::Gin() {
+  EnsureV8Initialized();
+  isolate_ = v8::Isolate::New();
+  v8::ResourceConstraints constraints;
+  constraints.ConfigureDefaults(base::SysInfo::AmountOfPhysicalMemory());
+  v8::SetResourceConstraints(isolate_, &constraints);
+  v8::Isolate::Scope isolate_scope(isolate_);
+  v8::HandleScope handle_scope(isolate_);
+  new PerIsolateData(isolate_);
+}
+
+Gin::~Gin() {
+  isolate_->Dispose();
+}
+
+}  // namespace gin