ozone: Implement PlatformObject<T> for platform-specific objects

ui/ozone/platform_object.h

Index: ui/ozone/platform_object.h
diff --git a/ui/ozone/platform_object.h b/ui/ozone/platform_object.h
new file mode 100644
index 0000000000000000000000000000000000000000..3d3a65ae5240cd2e1aadb175718f220b8aa6f607
--- /dev/null
+++ b/ui/ozone/platform_object.h
@@ -0,0 +1,34 @@
+// Copyright 2014 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 UI_OZONE_PLATFORM_OBJECT_H_
+#define UI_OZONE_PLATFORM_OBJECT_H_
+
+#include "base/memory/scoped_ptr.h"
+
+namespace ui {
+
+// Create an instance of platform specific object.
+//
+// This calls a static constructor function based on the --ozone-platform flag.
+//
+// For the platform called "foo", PlatformObject<PlatformWidget> will ultimately
+// call the function with signature
+//
+//   Bar* CreatePlatformWidgetFoo();
+//
+// A definition of this function for each compiled platform must be provided, or
+// link errors will result.
+//
+// To find the right constructor function, this uses static data defined in the
+// source file generated by the generate_constructor_list.py.
+template <class T>
+class PlatformObject {
+ public:
+  static scoped_ptr<T> Create();
+};
+
+}  // namespace ui
+
+#endif  // UI_OZONE_PLATFORM_OBJECT_H_