Remove the retargeting notification

chrome/browser/chrome_notification_types.h

Index: chrome/browser/chrome_notification_types.h
diff --git a/chrome/browser/chrome_notification_types.h b/chrome/browser/chrome_notification_types.h
index 39640ae75e3757b0b64e6e15d8b106cd2914c4e1..6c46a7101f7774c114017b9596b3828797fcf4df 100644
--- a/chrome/browser/chrome_notification_types.h
+++ b/chrome/browser/chrome_notification_types.h
@@ -83,12 +83,6 @@ enum NotificationType {
   // traversal. The source is the browser, there are no details.
   NOTIFICATION_FOCUS_RETURNED_TO_BROWSER,
 
-  // A new tab is created from an existing tab to serve as a target of a
-  // navigation that is about to happen. The source will be a Source<Profile>
-  // corresponding to the profile in which the new tab will live.  Details in
-  // the form of a RetargetingDetails object are provided.
-  NOTIFICATION_RETARGETING,
-
   // Application-wide ----------------------------------------------------------
 
   // This message is sent when the application is terminating (the last