Call ARC icon to load ARC icon directly.

Remove LoadIconFromResource, and don't load the default icon for ARC
apps.

BUG=1033215

Change-Id: I7e3d81b97aecf5a75b0fd227072f877c3e6167af
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1981526Reviewed-by: Dominick Ng <dominickn@chromium.org>
Commit-Queue: Nancy Wang <nancylingwang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#727933}

chrome/browser/apps/app_service/arc_apps.cc

@@ -343,11 +343,6 @@ void ArcApps::LoadIcon(const std::string& app_id,
   if (app_id == arc::kPlayStoreAppId) {
     LoadPlayStoreIcon(icon_compression, size_hint_in_dip, icon_effects,
                       std::move(callback));
-  } else if (allow_placeholder_icon) {
-    constexpr bool is_placeholder_icon = true;
-    LoadIconFromResource(icon_compression, size_hint_in_dip,
-                         IDR_APP_DEFAULT_ICON, is_placeholder_icon,
-                         icon_effects, std::move(callback));
   } else {
     arc_icon_once_loader_.LoadIcon(
         app_id, size_hint_in_dip, icon_compression,