Migrate off BrowserThread::DeleteSoon in /chrome/browser/ui/webui/discards

Instead use base::DeleteSoon which enforces usage of TaskTraits.

This CL is a no-op as-is. It was recently discovered however that some
callers did BrowserThread::DeleteSoon() with pending tasks running on
different task queues (different traits  -- e.g.

TaskTraits to make this more obvious. Please review whether calls in
this CL can be migrated as-is or need additional traits to match
potentially pending tasks.

Split from https://chromium-review.googlesource.com/c/chromium/src/+/1894109
for cursory review.

This CL was uploaded by git cl split.

R=fdoray@chromium.org


TaskPriority: :BEST_EFFORT) which can result in out-of-order deletion...
BrowserThread: :DeleteSoon() is being migrated to base::DeleteSoon() w/
Bug: 1019767
Change-Id: Idfdf967c4953e8293e420579ba6abc2d6f9e66f1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1895650
Auto-Submit: Gabriel Charette <gab@chromium.org>
Reviewed-by: François Doray <fdoray@chromium.org>
Commit-Queue: Gabriel Charette <gab@chromium.org>
Cr-Commit-Position: refs/heads/master@{#711792}

chrome/browser/ui/webui/discards/graph_dump_impl.cc

@@ -207,8 +207,8 @@ void DiscardsGraphDumpImpl::OnTakenFromGraph(
 
   // The favicon helper must be deleted on the UI thread.
   if (favicon_request_helper_) {
-    content::BrowserThread::DeleteSoon(content::BrowserThread::UI, FROM_HERE,
-                                       std::move(favicon_request_helper_));
+    base::DeleteSoon(FROM_HERE, {content::BrowserThread::UI},
+                     std::move(favicon_request_helper_));
   }
 
   graph_ = nullptr;