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..3c1530f73a519d910d1a3536571c5499f0513bac 100644
--- a/ui/message_center/notification.h
+++ b/ui/message_center/notification.h
@@ -10,6 +10,7 @@
 #include <string>
 #include <vector>
 
+#include "base/strings/nullable_string16.h"
 #include "base/strings/string16.h"
 #include "base/time/time.h"
 #include "base/values.h"
@@ -29,9 +30,13 @@ 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;

[Peter Beverloo, 2016/09/22 18:07:56]

Please define the default value, since this is a scalar.

[awdf, 2016/09/23 15:24:56]

Done.

+  base::NullableString16 placeholder;
 
   ButtonInfo(const base::string16& title);
 };