[CodeHealth] Remove unused callback in PermissionDialogDelegate

Bug: 1152263
Change-Id: I6b4db7e7fd955a5016b54775993447a5b21d1580
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2585817Reviewed-by: Cait Phillips <caitkp@chromium.org>
Commit-Queue: Yi Gu <yigu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#836630}

components/permissions/android/permission_dialog_delegate.h

@@ -28,9 +28,6 @@ namespace permissions {
 // decision.
 class PermissionDialogDelegate : public content::WebContentsObserver {
  public:
-  using PermissionSetCallback =
-      base::Callback<void(bool, permissions::PermissionAction)>;
-
   // The interface for creating a modal dialog when the PermissionRequestManager
   // is enabled.
   static void Create(content::WebContents* web_contents,