Signed exchange: Remove stale comment in NavigationURLLoaderImpl

Bug: 849935
Change-Id: Ifc480bba69fa9b15aa0b0adb9b0c6a6cb28441b0
Reviewed-on: https://chromium-review.googlesource.com/c/1264136Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Commit-Queue: Kunihiko Sakamoto <ksakamoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#597018}

content/browser/loader/navigation_url_loader_impl.cc

@@ -677,11 +677,6 @@ class NavigationURLLoaderImpl::URLLoaderRequestController
     }
 
     if (signed_exchange_utils::IsSignedExchangeHandlingEnabled()) {
-      // Signed Exchange is currently disabled when Network Service is enabled
-      // (https://crbug.com/849935), but still create
-      // SignedExchangeRequestHandler in order to show error message (and
-      // devtools warning) to users.
-
       // It is safe to pass the callback of CreateURLLoaderThrottles with the
       // unretained |this|, because the passed callback will be used by a
       // SignedExchangeHandler which is indirectly owned by |this| until its