Update Sad Tab help text and link.

views/layout/center_layout.h

+// Copyright (c) 2011 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 VIEWS_LAYOUT_CENTER_LAYOUT_H_
+#define VIEWS_LAYOUT_CENTER_LAYOUT_H_
+#pragma once
+
+#include "views/layout/layout_manager.h"
+#include "views/view.h"
+
+namespace gfx {
+class Size;
+}
+
+namespace views {
+
+// A layout manager that layouts a single child at the center of the host view.
+// The child's size is limited by the host's local bounds and insets.
+class VIEWS_EXPORT CenterLayout : public LayoutManager {
+ public:
+  CenterLayout();
+  virtual ~CenterLayout();
+
+  // Overridden from LayoutManager:
+  virtual void Layout(View* host) OVERRIDE;
+  virtual gfx::Size GetPreferredSize(View* host) OVERRIDE;
+  virtual int GetPreferredHeightForWidth(View* host, int width) OVERRIDE;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(CenterLayout);
+};
+
+} // namespace views
+
+#endif // VIEWS_LAYOUT_CENTER_LAYOUT_H_