Pushed InkDropHost inheritence up to CustomButton.

ui/views/controls/button/image_button.cc

Index: ui/views/controls/button/image_button.cc
diff --git a/ui/views/controls/button/image_button.cc b/ui/views/controls/button/image_button.cc
index ce7a545cc1f530321b032567ae91d0f1d9deab0f..e9d4f36c92bee7283cc41fba93c008757c0aa014 100644
--- a/ui/views/controls/button/image_button.cc
+++ b/ui/views/controls/button/image_button.cc
@@ -108,6 +108,9 @@ void ImageButton::OnPaint(gfx::Canvas* canvas) {
   // Call the base class first to paint any background/borders.
   View::OnPaint(canvas);
 
+  // TODO(estade|tdanderson|bruthig): The ink drop layer should be positioned
+  // behind the button's image which means the image needs to be painted to its
+  // own layer instead of to the Canvas.
   gfx::ImageSkia img = GetImageToPaint();
 
   if (!img.isNull()) {