Wholesale move sky/engine/tonic to tonic

tonic/dart_gc_context.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 <utility>
+
+#include "tonic/dart_gc_context.h"
+
+namespace blink {
+
+DartGCContext::DartGCContext() : builder_(Dart_NewWeakReferenceSetBuilder()) {
+}
+
+DartGCContext::~DartGCContext() {
+}
+
+Dart_WeakReferenceSet DartGCContext::AddToSetForRoot(
+    const void* root,
+    Dart_WeakPersistentHandle handle) {
+  const auto& result = references_.insert(std::make_pair(root, nullptr));
+  if (!result.second) {
+    // Already present.
+    Dart_AppendToWeakReferenceSet(result.first->second, handle, handle);
+    return result.first->second;
+  }
+  result.first->second = Dart_NewWeakReferenceSet(builder_, handle, handle);
+  return result.first->second;
+}
+
+}  // namespace blink