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

base/metrics/field_trial.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 "base/metrics/field_trial.h"
 
 #include "base/build_time.h"
 #include "base/logging.h"
 #include "base/rand_util.h"
 #include "base/sha1.h"
@@ skipping 300 matching lines @@
   if (field_trial)
     return field_trial->group();
   return FieldTrial::kNotFinalized;
 }
 
 // static
 std::string FieldTrialList::FindFullName(const std::string& name) {
   FieldTrial* field_trial = Find(name);
   if (field_trial)
     return field_trial->group_name();
-  return "";
+  return std::string();
 }
 
 // static
 bool FieldTrialList::TrialExists(const std::string& name) {
   return Find(name) != NULL;
 }
 
 // static
 void FieldTrialList::StatesToString(std::string* output) {
   FieldTrial::ActiveGroups active_groups;
@@ skipping 151 matching lines @@
     used_without_global_ = true;
     return;
   }
   AutoLock auto_lock(global_->lock_);
   DCHECK(!global_->PreLockedFind(trial->trial_name()));
   trial->AddRef();
   global_->registered_[trial->trial_name()] = trial;
 }
 
 }  // namespace base