views: Add optional overlay image to ImageButton

ui/views/examples/button_example.h

Index: ui/views/examples/button_example.h
diff --git a/ui/views/examples/button_example.h b/ui/views/examples/button_example.h
index 64b914fb099d88989a0f26ceca8a55446f8a7b6d..da0970ca4ba3222f719bcf1edad077dd86dbff26 100644
--- a/ui/views/examples/button_example.h
+++ b/ui/views/examples/button_example.h
@@ -12,6 +12,8 @@
 #include "ui/views/examples/example_base.h"
 
 namespace views {
+
+class ImageButton;
 class View;
 
 namespace examples {
@@ -29,15 +31,16 @@ class ButtonExample : public ExampleBase, public ButtonListener {
   // Overridden from ButtonListener:
   virtual void ButtonPressed(Button* sender, const Event& event) OVERRIDE;
 
-  // The only control in this test.
-  TextButton* button_;
+  // Example buttons.
+  TextButton* text_button_;
+  ImageButton* image_button_;
 
   // Values used to modify the look and feel of the button.
   TextButton::TextAlignment alignment_;
   bool use_native_theme_border_;
   const SkBitmap* icon_;
 
-  // The number of times the button is pressed.
+  // The number of times the buttons are pressed.
   int count_;
 
   DISALLOW_COPY_AND_ASSIGN(ButtonExample);