[Merge-M54] Fix crash on item drag in shelf.

chrome/browser/ui/ash/chrome_launcher_prefs.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/ash/chrome_launcher_prefs.h"
 
 #include <stddef.h>
 
 #include <set>
 
@@ skipping 648 matching lines @@
   DCHECK(profile);
   DCHECK(!app_id.empty());
   app_list::AppListSyncableService* app_service =
       app_list::AppListSyncableServiceFactory::GetForProfile(profile);
   app_service->SetPinPosition(app_id, syncer::StringOrdinal());
 }
 
 void SetPinPosition(Profile* profile,
                     const std::string& app_id,
                     const std::string& app_id_before,
-                    const std::string& app_id_after) {
+                    const std::vector<std::string>& app_ids_after) {
   DCHECK(profile);
   DCHECK(!app_id.empty());
   DCHECK_NE(app_id, app_id_before);
-  DCHECK_NE(app_id, app_id_after);
-  DCHECK(app_id_before.empty() || app_id_before != app_id_after);
 
   app_list::AppListSyncableService* app_service =
       app_list::AppListSyncableServiceFactory::GetForProfile(profile);
   // Some unit tests may not have this service.
   if (!app_service)
     return;
 
   syncer::StringOrdinal position_before =
       app_id_before.empty() ? syncer::StringOrdinal()
                             : app_service->GetPinPosition(app_id_before);
-  syncer::StringOrdinal position_after =
-      app_id_after.empty() ? syncer::StringOrdinal()
-                           : app_service->GetPinPosition(app_id_after);
+  syncer::StringOrdinal position_after;
+  for (const auto& app_id_after : app_ids_after) {
+    DCHECK_NE(app_id_after, app_id);
+    DCHECK_NE(app_id_after, app_id_before);
+    syncer::StringOrdinal position = app_service->GetPinPosition(app_id_after);
+    DCHECK(position.IsValid());
+    if (!position.IsValid()) {
+      LOG(ERROR) << "Sync pin position was not found for " << app_id_after;
+      continue;
+    }
+    if (!position_before.IsValid() || !position.Equals(position_before)) {
+      position_after = position;
+      break;
+    }
+  }
 
   syncer::StringOrdinal pin_position;
   if (position_before.IsValid() && position_after.IsValid())
     pin_position = position_before.CreateBetween(position_after);
   else if (position_before.IsValid())
     pin_position = position_before.CreateAfter();
   else if (position_after.IsValid())
     pin_position = position_after.CreateBefore();
   else
     pin_position = syncer::StringOrdinal::CreateInitialOrdinal();
   app_service->SetPinPosition(app_id, pin_position);
 }
 
 }  // namespace launcher
 }  // namespace ash