Remove unused PageInfoUI tab ID enum.

PageInfo used to have tabs, but it doesn't anymore. This removes a
lingering unused enum.

Change-Id: I1d1c3722436ae25532fd85a84704bfc5e839f5cc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1692871
Commit-Queue: Joe DeBlasio <jdeblasio@chromium.org>
Commit-Queue: Mustafa Emre Acer <meacer@chromium.org>
Auto-Submit: Joe DeBlasio <jdeblasio@chromium.org>
Reviewed-by: Mustafa Emre Acer <meacer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#675770}

chrome/browser/ui/page_info/page_info_ui.h

@@ -37,14 +37,6 @@ class X509Certificate;
 // etc.).
 class PageInfoUI {
  public:
-  // The Page Info UI contains several tabs. Each tab is associated with
-  // a unique tab id. The enum |TabId| contains all the ids for the tabs.
-  enum TabId {
-    TAB_ID_PERMISSIONS = 0,
-    TAB_ID_CONNECTION,
-    NUM_TAB_IDS,
-  };
-
   enum class SecuritySummaryColor {
     RED,
     GREEN,