Re-land "Add a Color class to dart:sky."

sky/engine/core/painting/CanvasColor.cpp

Index: sky/engine/core/painting/CanvasColor.cpp
diff --git a/sky/engine/core/painting/CanvasColor.cpp b/sky/engine/core/painting/CanvasColor.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..9788da811c8b85efcc6dbc684970bfb19fa6deac
--- /dev/null
+++ b/sky/engine/core/painting/CanvasColor.cpp
@@ -0,0 +1,45 @@
+// 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/core/painting/CanvasColor.h"
+
+#include "sky/engine/core/script/dom_dart_state.h"
+#include "sky/engine/tonic/dart_builtin.h"
+#include "sky/engine/tonic/dart_error.h"
+#include "sky/engine/tonic/dart_value.h"
+
+namespace blink {
+
+// Convert dart_color => SkColor.
+CanvasColor DartConverter<CanvasColor, void>::FromArgumentsWithNullCheck(
+    Dart_NativeArguments args,
+    int index,
+    Dart_Handle& exception) {
+  CanvasColor result;
+
+  Dart_Handle dart_color = Dart_GetNativeArgument(args, index);
+  DCHECK(!LogIfError(dart_color));
+
+  Dart_Handle value =
+      Dart_GetField(dart_color, DOMDartState::Current()->value_handle());
+
+  uint64_t color = 0;
+  Dart_Handle rv = Dart_IntegerToUint64(value, &color);
+  DCHECK(!LogIfError(rv));
+  DCHECK(color <= 0xffffffff);
+
+  result.sk_color = static_cast<SkColor>(color);
+  return result;
+}
+
+void DartConverter<CanvasColor, void>::SetReturnValue(
+    Dart_NativeArguments args, unsigned val) {
+  Dart_Handle color_class = DOMDartState::Current()->color_class();
+  Dart_Handle constructor_args[] = { ToDart(val) };
+  Dart_SetReturnValue(args,
+                      Dart_New(color_class, Dart_Null(), 1, constructor_args));
+}
+
+} // namespace blink