favicons: removes some dead code

This code has no use.

BUG=none
TEST=none

Change-Id: If31ffcf26cf8f6519216280e9ef0d0c3abe7f7fe
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2314119Reviewed-by: Evan Stade <estade@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#791005}

components/favicon/core/favicon_service_impl.cc

@@ -105,8 +105,6 @@ base::CancelableTaskTracker::TaskId FaviconServiceImpl::GetFavicon(
     favicon_base::FaviconResultsCallback callback,
     base::CancelableTaskTracker* tracker) {
   TRACE_EVENT0("browser", "FaviconServiceImpl::GetFavicon");
-  std::vector<GURL> icon_urls;
-  icon_urls.push_back(icon_url);
   return history_service_->GetFavicon(
       icon_url, icon_type, GetPixelSizesForFaviconScales(desired_size_in_dip),
       std::move(callback), tracker);