Merge the tonic layer from skydart branch back to master

sky/engine/tonic/dart_class_library.h

Index: sky/engine/tonic/dart_class_library.h
diff --git a/sky/engine/tonic/dart_class_library.h b/sky/engine/tonic/dart_class_library.h
new file mode 100644
index 0000000000000000000000000000000000000000..5a1b2125d86e2b0837ca64a9fd99b1da8aa799ab
--- /dev/null
+++ b/sky/engine/tonic/dart_class_library.h
@@ -0,0 +1,33 @@
+// 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.
+
+#ifndef SKY_ENGINE_TONIC_DART_CLASS_LIBRARY_H_
+#define SKY_ENGINE_TONIC_DART_CLASS_LIBRARY_H_
+
+#include "base/macros.h"
+#include "dart/runtime/include/dart_api.h"
+#include "sky/engine/tonic/dart_class_provider.h"
+#include "sky/engine/wtf/HashMap.h"
+
+namespace blink {
+struct DartWrapperInfo;
+
+class DartClassLibrary {
+ public:
+  explicit DartClassLibrary();
+  ~DartClassLibrary();
+
+  void set_provider(DartClassProvider* provider) { provider_ = provider; }
+  Dart_PersistentHandle GetClass(const DartWrapperInfo& info);
+
+ private:
+  DartClassProvider* provider_;
+  HashMap<const DartWrapperInfo*, Dart_PersistentHandle> cache_;
+
+  DISALLOW_COPY_AND_ASSIGN(DartClassLibrary);
+};
+
+}  // namespace blink
+
+#endif  // SKY_ENGINE_TONIC_DART_CLASS_LIBRARY_H_