Implement Non-Closable Notification

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 491943d6e07529f1399d54440aef7c64a799d89f..c7d2cc5b51af80b3d14cf0df5bec54706a30cb23 100644
--- a/ui/message_center/notification.h
+++ b/ui/message_center/notification.h
@@ -53,6 +53,7 @@ class MESSAGE_CENTER_EXPORT RichNotificationData {
   std::vector<ButtonInfo> buttons;
   bool should_make_spoken_feedback_for_popup_updates;
   bool clickable;
+  bool pinned;

[dewittj, 2016/02/10 00:03:15]

please document this field somewhere, I realize that not all fields are
documented but this one may have non-obvious implications.

[yoshiki, 2016/02/12 23:11:36]

Done.

   std::vector<int> vibration_pattern;
   bool silent;
 };
@@ -206,6 +207,9 @@ class MESSAGE_CENTER_EXPORT Notification {
     optional_fields_.clickable = clickable;
   }
 
+  bool pinned() const { return optional_fields_.pinned; }

[Miguel Garcia, 2016/02/10 10:00:54]

Would it make sense to ifdef these methods of CrOs? I understand why this is
needed for CrOs but I don't think we will want them on other platforms.

[yoshiki, 2016/02/12 23:11:36]

It is a chromeos only feature. Done.

+  void set_pinned(bool pinned) { optional_fields_.pinned = pinned; }
+
   NotificationDelegate* delegate() const { return delegate_.get(); }
 
   const RichNotificationData& rich_notification_data() const {