ui: Cleanup class/struct forward declarations

extensions/renderer/api_binding_types.h

Index: extensions/renderer/api_binding_types.h
diff --git a/extensions/renderer/api_binding_types.h b/extensions/renderer/api_binding_types.h
new file mode 100644
index 0000000000000000000000000000000000000000..447bb59e2c9a04af1c5bf5a17b6990d46ef08392
--- /dev/null
+++ b/extensions/renderer/api_binding_types.h
@@ -0,0 +1,24 @@
+// Copyright 2016 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 EXTENSIONS_RENDERER_API_BINDING_TYPES_H_
+#define EXTENSIONS_RENDERER_API_BINDING_TYPES_H_
+
+#include "base/callback.h"
+#include "v8/include/v8.h"
+
+namespace extensions {
+namespace binding {
+
+// A callback to execute the given v8::Function with the provided context and
+// arguments.
+using RunJSFunction = base::Callback<void(v8::Local<v8::Function>,
+                                          v8::Local<v8::Context>,
+                                          int argc,
+                                          v8::Local<v8::Value>[])>;
+
+}  // namespace binding
+}  // namespace extensions
+
+#endif  // EXTENSIONS_RENDERER_API_BINDING_TYPES_H_