Add MD ink drop ripple to shelf app items

ash/shelf/app_list_button.cc

Index: ash/shelf/app_list_button.cc
diff --git a/ash/shelf/app_list_button.cc b/ash/shelf/app_list_button.cc
index aa9e48c37cd078cebd7b655b766604209391b9c7..885b534f0ef1a4b3aea6bb8ff317e35c747a1fdc 100644
--- a/ash/shelf/app_list_button.cc
+++ b/ash/shelf/app_list_button.cc
@@ -10,6 +10,7 @@
 #include "ash/common/shelf/shelf_item_types.h"
 #include "ash/common/shelf/shelf_types.h"
 #include "ash/common/shelf/wm_shelf_util.h"
+#include "ash/shelf/ink_drop_button_listener.h"
 #include "ash/shelf/shelf_layout_manager.h"
 #include "ash/shelf/shelf_view.h"
 #include "ash/shelf/shelf_widget.h"
@@ -32,9 +33,11 @@ namespace ash {
 // Radius of the app list button circular background.
 const int kAppListButtonBackgroundRadius = 16;
 
-AppListButton::AppListButton(ShelfView* shelf_view)
-    : views::ImageButton(shelf_view),
+AppListButton::AppListButton(InkDropButtonListener* listener,
+                             ShelfView* shelf_view)
+    : views::ImageButton(nullptr),
       draw_background_as_active_(false),
+      listener_(listener),
       shelf_view_(shelf_view) {
   SetAccessibleName(
       app_list::switches::IsExperimentalAppListEnabled()
@@ -238,6 +241,12 @@ void AppListButton::GetAccessibleState(ui::AXViewState* state) {
   state->name = shelf_view_->GetTitleForView(this);
 }
 
+void AppListButton::NotifyClick(const ui::Event& event) {
+  ImageButton::NotifyClick(event);
+  if (listener_)
+    listener_->ButtonPressed(this, event, ink_drop());
+}
+
 void AppListButton::SetDrawBackgroundAsActive(
     bool draw_background_as_active) {
   if (draw_background_as_active_ == draw_background_as_active)