Implement progress bar spec (determinate and indeterminate).

ui/views/examples/progress_bar_example.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 UI_VIEWS_EXAMPLES_PROGRESS_BAR_EXAMPLE_H_
 #define UI_VIEWS_EXAMPLES_PROGRESS_BAR_EXAMPLE_H_
 
 #include "base/macros.h"
 #include "ui/views/controls/button/button.h"
 #include "ui/views/examples/example_base.h"
@@ skipping 12 matching lines @@
   // ExampleBase:
   void CreateExampleView(View* container) override;
 
  private:
   // ButtonListener:
   void ButtonPressed(Button* button, const ui::Event& event) override;
 
   Button* minus_button_;
   Button* plus_button_;
   ProgressBar* progress_bar_;
+  ProgressBar* indeterminate_progress_bar_;
   double current_percent_;
 
   DISALLOW_COPY_AND_ASSIGN(ProgressBarExample);
 };
 
 }  // namespace examples
 }  // namespace views
 
 #endif  // UI_VIEWS_EXAMPLES_PROGRESS_BAR_EXAMPLE_H_