Plumb through notification action types and placeholders on Android

ui/message_center/notification.h

Index: ui/message_center/notification.h
diff --git a/ui/message_center/notification.h b/ui/message_center/notification.h
index 93d255e56daa8439201c0348146a3df69e15ee7c..e88555cb609f3bf822dfa6e7711e66eb58c10dc3 100644
--- a/ui/message_center/notification.h
+++ b/ui/message_center/notification.h
@@ -29,11 +29,18 @@ struct MESSAGE_CENTER_EXPORT NotificationItem {
   NotificationItem(const base::string16& title, const base::string16& message);
 };
 
+enum class ButtonType { BUTTON, TEXT };
+
 struct MESSAGE_CENTER_EXPORT ButtonInfo {
   base::string16 title;
   gfx::Image icon;
+  ButtonType type = ButtonType::BUTTON;
+  base::string16 placeholder;
 
-  ButtonInfo(const base::string16& title);
+  explicit ButtonInfo(const base::string16& title);
+  ButtonInfo(const ButtonInfo& other);
+  ~ButtonInfo();
+  ButtonInfo& operator=(const ButtonInfo& other);
 };
 
 class MESSAGE_CENTER_EXPORT RichNotificationData {