Reland of "Added common layout framework for system menu rows."

ash/common/system/tray/tray_popup_layout_factory.h

+// 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 ASH_COMMON_SYSTEM_TRAY_TRAY_POPUP_LAYOUT_FACTORY_H_
+#define ASH_COMMON_SYSTEM_TRAY_TRAY_POPUP_LAYOUT_FACTORY_H_
+
+#include <memory>
+
+#include "ash/common/system/tray/tri_view.h"
+#include "base/macros.h"
+
+namespace views {
+class View;
+}  // namespace views
+
+namespace ash {
+
+// Factory functions for system menu row container views.
+class TrayPopupLayoutFactory {
+ public:
+  // Creates a default container view to be used most system menu rows. The
+  // caller takes over ownership of the created view.
+  //
+  // The returned view consists of 3 regions: START, CENTER, and END. Any child
+  // Views added to the START and END containers will be added horizonatlly and
+  // any Views added to the CENTER container will be added vertically.
+  //
+  // The START and END containers have a fixed width but can grow into the
+  // CENTER container if space is required and available.
+  //
+  // The CENTER container has a flexible width.
+  static TriView* CreateDefaultRowView();
+
+  // Configures the different |container| views with the default layout
+  // managers.
+  //
+  // This can be used by clients who need to embed portions of the default
+  // layout manager into a different container view, e.g. just the END layout
+  // into a clickable View.

[tdanderson, 2016/10/26 19:29:12]

nit: I think this comment needs updating (should not make direct mention of
'layout manager' ?)

[bruthig, 2016/10/26 21:24:16]

Moved to private and updated the comment.  Since the use case is still somewhat
ill-defined it is difficult to document it and so I removed it.  Will update as
needed in follow-up work.

+  static void ConfigureDefaultLayout(TriView* layout,
+                                     TriView::Container container);
+
+ private:
+  TrayPopupLayoutFactory();
+  ~TrayPopupLayoutFactory();
+
+  DISALLOW_COPY_AND_ASSIGN(TrayPopupLayoutFactory);
+};
+
+}  // namespace ash
+
+#endif  // ASH_COMMON_SYSTEM_TRAY_TRAY_POPUP_LAYOUT_FACTORY_H_