Rewrite std::string("") to std::string(), Linux edition.

chrome/browser/sync/test/integration/sync_extension_helper.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/sync/test/integration/sync_extension_helper.h"
 
 #include "base/file_util.h"
 #include "base/files/file_path.h"
 #include "base/logging.h"
 #include "base/values.h"
@@ skipping 45 matching lines @@
   SetupProfile(test->verifier());
 
   setup_completed_ = true;
 }
 
 std::string SyncExtensionHelper::InstallExtension(
     Profile* profile, const std::string& name, Manifest::Type type) {
   scoped_refptr<Extension> extension = GetExtension(profile, name, type);
   if (!extension.get()) {
     NOTREACHED() << "Could not install extension " << name;
-    return "";
+    return std::string();
   }
   profile->GetExtensionService()->OnExtensionInstalled(
       extension, syncer::StringOrdinal(), false /* no requirement errors */,
       false /* don't wait for idle to install */);
   return extension->id();
 }
 
 void SyncExtensionHelper::UninstallExtension(
     Profile* profile, const std::string& name) {
   ExtensionService::UninstallExtensionHelper(
@@ skipping 289 matching lines @@
     EXPECT_EQ(expected_id, extension->id());
     return NULL;
   }
   DVLOG(2) << "created extension with name = "
            << name << ", id = " << expected_id;
   (it->second)[name] = extension;
   id_to_name_[expected_id] = name;
   id_to_type_[expected_id] = type;
   return extension;
 }