CustomButton cleanup: make protected members private, create accessors

ui/app_list/views/search_box_view.cc

Index: ui/app_list/views/search_box_view.cc
diff --git a/ui/app_list/views/search_box_view.cc b/ui/app_list/views/search_box_view.cc
index 1676f0aa4c35766fd26bd80c3353e2e582caf32d..1825b4eb34d114e0b414d3538438714689e2b274 100644
--- a/ui/app_list/views/search_box_view.cc
+++ b/ui/app_list/views/search_box_view.cc
@@ -103,7 +103,7 @@ class SearchBoxImageButton : public views::ImageButton {
  private:
   // views::View overrides:
   void OnPaintBackground(gfx::Canvas* canvas) override {
-    if (state_ == STATE_HOVERED || state_ == STATE_PRESSED || selected_)
+    if (state() == STATE_HOVERED || state() == STATE_PRESSED || selected_)
       canvas->FillRect(gfx::Rect(size()), kSelectedColor);
   }