Merge the tonic layer from skydart branch back to master

sky/engine/tonic/dart_state.cc

+// Copyright 2015 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 "sky/engine/config.h"
+#include "sky/engine/tonic/dart_state.h"
+
+#include "sky/engine/tonic/dart_class_library.h"
+#include "sky/engine/tonic/dart_string_cache.h"
+#include "sky/engine/wtf/PassOwnPtr.h"
+
+namespace blink {
+
+DartState::Scope::Scope(DartState* dart_state) {
+}
+
+DartState::Scope::~Scope() {
+}
+
+DartState::DartState()
+    : isolate_(NULL),
+      class_library_(adoptPtr(new DartClassLibrary)),
+      string_cache_(adoptPtr(new DartStringCache)),
+      weak_factory_(this) {
+}
+
+DartState::~DartState() {
+}
+
+DartState* DartState::From(Dart_Isolate isolate) {
+  return static_cast<DartState*>(Dart_IsolateData(isolate));
+}
+
+DartState* DartState::Current() {
+  return static_cast<DartState*>(Dart_CurrentIsolateData());
+}
+
+base::WeakPtr<DartState> DartState::GetWeakPtr() {
+  return weak_factory_.GetWeakPtr();
+}
+
+}  // namespace blink