Do a "use DCHECK instead of CHECK" TODO

The TODO was introduced in 2015:
https://codereview.chromium.org/981893002

Change-Id: I6efe5e05cee5c6553050d35f2437a165d065c282
Reviewed-on: https://chromium-review.googlesource.com/c/1260522Reviewed-by: calamity <calamity@chromium.org>
Commit-Queue: Nigel Tao <nigeltao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#596512}

chrome/browser/ui/app_list/app_list_syncable_service.cc

@@ -389,8 +389,7 @@ bool AppListSyncableService::IsInitialized() const {
 void AppListSyncableService::BuildModel() {
   InitFromLocalStorage();
 
-  // TODO(calamity): make this a DCHECK after a dev channel release.
-  CHECK(IsExtensionServiceReady());
+  DCHECK(IsExtensionServiceReady());
   AppListClientImpl* client = AppListClientImpl::GetInstance();
   AppListControllerDelegate* controller = client;
   apps_builder_ = std::make_unique<ExtensionAppModelBuilder>(controller);