ui: Cleanup class/struct forward declarations

ash/common/shelf/overflow_button.cc

Index: ash/common/shelf/overflow_button.cc
diff --git a/ash/common/shelf/overflow_button.cc b/ash/common/shelf/overflow_button.cc
index 0af3880a51da2b3409c4006648f148bf7630ab7a..607d07a1f1505f5437f06b971efea7456ab65dfe 100644
--- a/ash/common/shelf/overflow_button.cc
+++ b/ash/common/shelf/overflow_button.cc
@@ -26,6 +26,7 @@
 #include "ui/gfx/transform.h"
 #include "ui/gfx/vector_icons_public.h"
 #include "ui/views/animation/flood_fill_ink_drop_ripple.h"
+#include "ui/views/animation/ink_drop_impl.h"
 
 namespace ash {
 
@@ -82,6 +83,10 @@ void OverflowButton::OnPaint(gfx::Canvas* canvas) {
   PaintForeground(canvas, bounds);
 }
 
+std::unique_ptr<views::InkDrop> OverflowButton::CreateInkDrop() {
+  return CreateDefaultFloodFillInkDropImpl();
+}
+
 std::unique_ptr<views::InkDropRipple> OverflowButton::CreateInkDropRipple()
     const {
   return base::MakeUnique<views::FloodFillInkDropRipple>(
@@ -96,10 +101,6 @@ bool OverflowButton::ShouldEnterPushedState(const ui::Event& event) {
   return CustomButton::ShouldEnterPushedState(event);
 }
 
-bool OverflowButton::ShouldShowInkDropHighlight() const {
-  return false;
-}
-
 void OverflowButton::NotifyClick(const ui::Event& event) {
   CustomButton::NotifyClick(event);
   shelf_view_->ButtonPressed(this, event, GetInkDrop());