chore: move the view APIs to their own directory (#14722)

* chore: move the view APIs to their own directory

* move view api cpp files

atom/browser/api/views/atom_api_box_layout.h

@@ -0,0 +1,40 @@
+// Copyright (c) 2018 GitHub, Inc.
+// Use of this source code is governed by the MIT license that can be
+// found in the LICENSE file.
+
+#ifndef ATOM_BROWSER_API_VIEWS_ATOM_API_BOX_LAYOUT_H_
+#define ATOM_BROWSER_API_VIEWS_ATOM_API_BOX_LAYOUT_H_
+
+#include "atom/browser/api/views/atom_api_layout_manager.h"
+#include "native_mate/handle.h"
+#include "ui/views/layout/box_layout.h"
+
+namespace atom {
+
+namespace api {
+
+class View;
+
+class BoxLayout : public LayoutManager {
+ public:
+  static mate::WrappableBase* New(mate::Arguments* args,
+                                  views::BoxLayout::Orientation orientation);
+
+  static void BuildPrototype(v8::Isolate* isolate,
+                             v8::Local<v8::FunctionTemplate> prototype);
+
+  void SetFlexForView(mate::Handle<View> view, int flex);
+
+ protected:
+  explicit BoxLayout(views::BoxLayout::Orientation orientation);
+  ~BoxLayout() override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(BoxLayout);
+};
+
+}  // namespace api
+
+}  // namespace atom
+
+#endif  // ATOM_BROWSER_API_VIEWS_ATOM_API_BOX_LAYOUT_H_