Delete NOTIFICATION_TAB_ADDED

Recent changes have removed its usage throughout the codebase.

Bug: 268984
Change-Id: Id6b211af5e99d8774f68db7235196f869ca782b5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1753548Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Evan Stade <estade@chromium.org>
Cr-Commit-Position: refs/heads/master@{#687284}

chrome/browser/chrome_notification_types.h

@@ -90,10 +90,6 @@ enum NotificationType {
 
   // Tabs --------------------------------------------------------------------
 
-  // Sent when a tab is added to a WebContentsDelegate. The source is the
-  // WebContentsDelegate and the details is the added WebContents.
-  NOTIFICATION_TAB_ADDED,
-
   // This notification is sent after a tab has been appended to the tab_strip.
   // The source is a Source<WebContents> of the tab being added. There
   // are no details.

chrome/browser/ui/browser_navigator.cc

@@ -714,13 +714,6 @@ void Navigate(NavigateParams* params) {
     }
   }
 
-  if (params->disposition != WindowOpenDisposition::CURRENT_TAB) {
-    content::NotificationService::current()->Notify(
-        chrome::NOTIFICATION_TAB_ADDED,
-        content::Source<content::WebContentsDelegate>(params->browser),
-        content::Details<WebContents>(contents_to_navigate_or_insert));
-  }
-
   params->navigated_or_inserted_contents = contents_to_navigate_or_insert;
 }