Defend against deleting the default search provider when merging duplicate TURLs.

chrome/browser/search_engines/template_url_service_sync_unittest.cc

 // Copyright (c) 2011 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 "base/memory/scoped_ptr.h"
 #include "base/string_util.h"
 #include "base/time.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/search_engines/template_url.h"
 #include "chrome/browser/search_engines/template_url_service.h"
@@ skipping 1257 matching lines @@
   EXPECT_TRUE(model()->is_default_search_managed());
 
   // Go unmanaged. Ensure that the DSP changes to the expected pending entry
   // from Sync.
   const TemplateURL* expected_default =
       model()->GetTemplateURLForGUID("newdefault");
   RemoveManagedDefaultSearchPreferences(model(), profile_a_.get());
 
   EXPECT_EQ(expected_default, model()->GetDefaultSearchProvider());
 }
+
+TEST_F(TemplateURLServiceSyncTest, SyncMergeDeletesDefault) {
+  // If the value from Sync is a duplicate of the local default and is newer, it
+  // should safely replace the local value and set as the new default.
+  TemplateURL* default_turl =
+      CreateTestTemplateURL("key1", "http://key1.com", "whateverguid", 10);
+  model()->Add(default_turl);
+  model()->SetDefaultSearchProvider(default_turl);
+
+  // The key1 entry should be a duplicate of the default.
+  model()->MergeDataAndStartSyncing(
+      syncable::SEARCH_ENGINES,
+      CreateInitialSyncData(),
+      processor());
+
+  EXPECT_EQ(3U, model()->GetAllSyncData(syncable::SEARCH_ENGINES).size());
+  EXPECT_FALSE(model()->GetTemplateURLForGUID("whateverguid"));
+  EXPECT_EQ(model()->GetDefaultSearchProvider(),
+            model()->GetTemplateURLForGUID("key1"));
+}