Wholesale move sky/engine/tonic to tonic

tonic/dart_string_cache.h

Index: tonic/dart_string_cache.h
diff --git a/tonic/dart_string_cache.h b/tonic/dart_string_cache.h
new file mode 100644
index 0000000000000000000000000000000000000000..5ec219e12b8bcd33e75ac40dc49fffbc554d0f32
--- /dev/null
+++ b/tonic/dart_string_cache.h
@@ -0,0 +1,48 @@
+// 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_STRING_CACHE_H_
+#define SKY_ENGINE_TONIC_DART_STRING_CACHE_H_
+
+#include "base/logging.h"
+#include "dart/runtime/include/dart_api.h"
+#include "sky/engine/wtf/HashMap.h"
+#include "sky/engine/wtf/RefPtr.h"
+#include "sky/engine/wtf/text/StringHash.h"
+#include "sky/engine/wtf/text/StringImpl.h"
+
+namespace blink {
+
+// DartStringCache maintains a mapping between WTF Strings and Dart strings.
+// When you create a Dart string from a WTF String, the underlying character
+// data is shared between the two systems.
+class DartStringCache {
+ public:
+  DartStringCache();
+  ~DartStringCache();
+
+  Dart_WeakPersistentHandle Get(StringImpl* string_impl,
+                                bool auto_scope = true) {
+    DCHECK(string_impl);
+    if (last_string_impl_.get() == string_impl)
+      return last_dart_string_;
+    return GetSlow(string_impl, auto_scope);
+  }
+
+ private:
+  Dart_WeakPersistentHandle GetSlow(StringImpl* string_impl, bool auto_scope);
+  static void FinalizeCacheEntry(void*, Dart_WeakPersistentHandle, void* peer);
+
+  typedef HashMap<StringImpl*, Dart_WeakPersistentHandle> StringCache;
+
+  StringCache cache_;
+  Dart_WeakPersistentHandle last_dart_string_;
+  RefPtr<StringImpl> last_string_impl_;
+
+  DISALLOW_COPY_AND_ASSIGN(DartStringCache);
+};
+
+}  // namespace blink
+
+#endif  // SKY_ENGINE_TONIC_DART_STRING_CACHE_H_