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

ash/common/system/tray/tray_popup_layout_factory.h

Index: ash/common/system/tray/tray_popup_layout_factory.h
diff --git a/ash/common/system/tray/tray_popup_layout_factory.h b/ash/common/system/tray/tray_popup_layout_factory.h
new file mode 100644
index 0000000000000000000000000000000000000000..f279be6da57eb3c1286239428cd6309f831507ee
--- /dev/null
+++ b/ash/common/system/tray/tray_popup_layout_factory.h
@@ -0,0 +1,49 @@
+// 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();
+
+ private:
+  TrayPopupLayoutFactory();
+  ~TrayPopupLayoutFactory();
+
+  // Configures the specified |container| view with the default layout. Used by
+  // CreateDefaultRowView().
+  static void ConfigureDefaultLayout(TriView* tri_view,
+                                     TriView::Container container);
+
+  DISALLOW_COPY_AND_ASSIGN(TrayPopupLayoutFactory);
+};
+
+}  // namespace ash
+
+#endif  // ASH_COMMON_SYSTEM_TRAY_TRAY_POPUP_LAYOUT_FACTORY_H_