[App Management] Correctly label Play Store as a system app.

This CL modifies the function that determins the install source of an
ARC app. This handles the special case of the Play Store app, which is
classified as a default app on the Android side, but cannot be
uninstalled as it's a system image app.

Bug: 1009397
Change-Id: Iaf7e92d46596b85f09a46c724a17bc75f55991ad
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1837552Reviewed-by: Dominick Ng <dominickn@chromium.org>
Commit-Queue: Jeevan Shikaram <jshikaram@chromium.org>
Cr-Commit-Position: refs/heads/master@{#702604}

chrome/browser/apps/app_service/arc_apps.cc

@@ -468,6 +468,11 @@ void ArcApps::LoadPlayStoreIcon(apps::mojom::IconCompression icon_compression,
 
 apps::mojom::InstallSource GetInstallSource(const ArcAppListPrefs* prefs,
                                             const std::string& package_name) {
+  // TODO(crbug.com/1010821): Create a generic check for kSystem apps.
+  if (prefs->GetAppIdByPackageName(package_name) == arc::kPlayStoreAppId) {
+    return apps::mojom::InstallSource::kSystem;
+  }
+
   if (prefs->IsDefault(package_name)) {
     return apps::mojom::InstallSource::kDefault;
   }