Remove some unused constants from message center.

Bug: none
Change-Id: I1121e7b64cceb1c70e9a8115d9f9cc9d63716133
Reviewed-on: https://chromium-review.googlesource.com/568903Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Commit-Queue: Evan Stade <estade@chromium.org>
Cr-Commit-Position: refs/heads/master@{#486190}

ui/message_center/views/message_view.h

@@ -30,12 +30,6 @@ namespace message_center {
 class Notification;
 class MessageCenterController;
 
-// Individual notifications constants.
-const int kPaddingBetweenItems = 10;
-const int kPaddingHorizontal = 18;
-const int kWebNotificationButtonWidth = 32;
-const int kWebNotificationIconSize = 40;
-
 // An base class for a notification entry. Contains background and other
 // elements shared by derived notification views.
 class MESSAGE_CENTER_EXPORT MessageView