[WIP: not for review] Reduce re-layout

ui/views/examples/multiline_example.h

 // Copyright 2013 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_EXAMPLES_MULTILINE_EXAMPLE_H_
 #define UI_VIEWS_EXAMPLES_MULTILINE_EXAMPLE_H_
 
 #include "base/macros.h"
 #include "ui/views/controls/button/button.h"
 #include "ui/views/controls/textfield/textfield_controller.h"
 #include "ui/views/examples/example_base.h"
 
+namespace gfx {
+class RenderText;
+}
+
 namespace views {
 
 class Checkbox;
 class Label;
 
 namespace examples {
 
 // An example that compares the multiline rendering of different controls.
 class VIEWS_EXAMPLES_EXPORT MultilineExample : public ExampleBase,
                                                public TextfieldController,
                                                public ButtonListener {
  public:
-  MultilineExample();
+  explicit MultilineExample(const char* name);
   ~MultilineExample() override;
 
   // ExampleBase:
   void CreateExampleView(View* container) override;
 
   // ButtonListener:
   void ButtonPressed(Button* sender, const ui::Event& event) override;
 
- private:
+ protected:
   class RenderTextView;
 
+  virtual RenderTextView* CreateTextView();
+
   // TextfieldController:
   void ContentsChanged(Textfield* sender,
                        const base::string16& new_contents) override;
 
+ private:
   RenderTextView* render_text_view_;
   Label* label_;
   Textfield* textfield_;
 
   // Checkbox to enable and disable text rendering in |label_|.
   Checkbox* label_checkbox_;
 
   DISALLOW_COPY_AND_ASSIGN(MultilineExample);
 };
 
+// A simple View that hosts a RenderText object.
+class MultilineExample::RenderTextView : public View {
+ public:
+  RenderTextView();
+  ~RenderTextView() override;
+
+  void SetText(const base::string16& new_contents);
+  gfx::RenderText* render_text() { return render_text_.get(); }
+
+  // View:
+  void OnPaint(gfx::Canvas* canvas) override;
+  gfx::Size GetPreferredSize() const override;
+  int GetHeightForWidth(int w) const override;
+  void OnBoundsChanged(const gfx::Rect& previous_bounds) override;
+
+ private:
+  std::unique_ptr<gfx::RenderText> render_text_;
+
+  DISALLOW_COPY_AND_ASSIGN(RenderTextView);
+};
+
 }  // namespace examples
 }  // namespace views
 
 #endif  // UI_VIEWS_EXAMPLES_MULTILINE_EXAMPLE_H_