Attempt 2 at:

views/controls/button/image_button.h

 // Copyright (c) 2010 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_CONTROLS_BUTTON_IMAGE_BUTTON_H_
 #define VIEWS_CONTROLS_BUTTON_IMAGE_BUTTON_H_
 
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "views/controls/button/custom_button.h"
 
 namespace views {
 
 // An image button.
 
 // Note that this type of button is not focusable by default and will not be
 // part of the focus chain.  Call SetFocusable(true) to make it part of the
 // focus chain.
 
 class ImageButton : public CustomButton {
  public:
+  enum HorizontalAlignment { ALIGN_LEFT = 0,
+                             ALIGN_CENTER,
+                             ALIGN_RIGHT, };
+
+  enum VerticalAlignment { ALIGN_TOP = 0,
+                           ALIGN_MIDDLE,
+                           ALIGN_BOTTOM };
+
   explicit ImageButton(ButtonListener* listener);
   virtual ~ImageButton();
 
   // Set the image the button should use for the provided state.
   virtual void SetImage(ButtonState aState, const SkBitmap* anImage);
 
   // Set the background details.
   void SetBackground(SkColor color,
                      const SkBitmap* image,
                      const SkBitmap* mask);
 
-  enum HorizontalAlignment { ALIGN_LEFT = 0,
-                             ALIGN_CENTER,
-                             ALIGN_RIGHT, };
-
-  enum VerticalAlignment { ALIGN_TOP = 0,
-                           ALIGN_MIDDLE,
-                           ALIGN_BOTTOM };
+  // Explicitly sets the background image.
+  void set_background_image(const SkBitmap& background) {
+    background_image_ = background;
+  }
 
   // Sets how the image is laid out within the button's bounds.
   void SetImageAlignment(HorizontalAlignment h_align,
                          VerticalAlignment v_align);
 
   // Overridden from View:
   virtual gfx::Size GetPreferredSize();
   virtual void Paint(gfx::Canvas* canvas);
 
  protected:
@@ skipping 56 matching lines @@
   // The parent class's tooltip_text_ is displayed when not toggled, and
   // this one is shown when toggled.
   std::wstring toggled_tooltip_text_;
 
   DISALLOW_COPY_AND_ASSIGN(ToggleImageButton);
 };
 
 }  // namespace views
 
 #endif  // VIEWS_CONTROLS_BUTTON_IMAGE_BUTTON_H_