Added common layout framework for system menu rows.

ui/views/test/test_layout_manager.h

Index: ui/views/test/test_layout_manager.h
diff --git a/ui/views/test/test_layout_manager.h b/ui/views/test/test_layout_manager.h
new file mode 100644
index 0000000000000000000000000000000000000000..77e518986088ddda7cea3987f40131ad34603d3c
--- /dev/null
+++ b/ui/views/test/test_layout_manager.h
@@ -0,0 +1,45 @@
+// 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 UI_VIEWS_TEST_TEST_LAYOUT_MANAGER_H_
+#define UI_VIEWS_TEST_TEST_LAYOUT_MANAGER_H_
+
+#include "ui/gfx/geometry/size.h"
+#include "ui/views/layout/layout_manager.h"
+
+namespace views {
+namespace test {
+
+// A stub layout manager that returns a specific preferred size and height for
+// width.
+class TestLayoutManager : public LayoutManager {
+ public:
+  TestLayoutManager();
+  ~TestLayoutManager() override;
+
+  void set_preferred_size(const gfx::Size& size) { preferred_size_ = size; }
+
+  void set_preferred_height_for_width(int height) {
+    preferred_height_for_width_ = height;
+  }
+
+  // LayoutManager:
+  void Layout(View* host) override;
+  gfx::Size GetPreferredSize(const View* host) const override;
+  int GetPreferredHeightForWidth(const View* host, int width) const override;
+
+ private:
+  // The return value of GetPreferredSize();
+  gfx::Size preferred_size_ = gfx::Size(0, 0);

[sky, 2016/10/20 15:59:11]

Why the = gfx::Size(0, 0)? Isn't that the default?

[bruthig, 2016/10/20 19:01:34]

Removed.

+
+  // The return value for GetPreferredHeightForWidth().
+  int preferred_height_for_width_ = 0;
+
+  DISALLOW_COPY_AND_ASSIGN(TestLayoutManager);
+};
+
+}  // namespace test
+}  // namespace views
+
+#endif  // UI_VIEWS_TEST_TEST_LAYOUT_MANAGER_H_