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

base/metrics/field_trial_unittest.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/message_loop.h"
 #include "base/rand_util.h"
 #include "base/run_loop.h"
 #include "base/stringprintf.h"
@@ skipping 68 matching lines @@
   const char* name2 = "name 2 test";
   EXPECT_FALSE(FieldTrialList::Find(name1));
   EXPECT_FALSE(FieldTrialList::Find(name2));
 
   FieldTrial* trial1 = FieldTrialList::FactoryGetFieldTrial(
       name1, 10, "default name 1 test", next_year_, 12, 31, NULL);
   EXPECT_EQ(FieldTrial::kNotFinalized, trial1->group_);
   EXPECT_EQ(name1, trial1->trial_name());
   EXPECT_EQ("", trial1->group_name_internal());
 
-  trial1->AppendGroup("", 7);
+  trial1->AppendGroup(std::string(), 7);
 
   EXPECT_EQ(trial1, FieldTrialList::Find(name1));
   EXPECT_FALSE(FieldTrialList::Find(name2));
 
   FieldTrial* trial2 = FieldTrialList::FactoryGetFieldTrial(
       name2, 10, "default name 2 test", next_year_, 12, 31, NULL);
   EXPECT_EQ(FieldTrial::kNotFinalized, trial2->group_);
   EXPECT_EQ(name2, trial2->trial_name());
   EXPECT_EQ("", trial2->group_name_internal());
 
@@ skipping 114 matching lines @@
   int group_count(10);
 
   int default_group_number = -1;
   FieldTrial* trial = FieldTrialList::FactoryGetFieldTrial(
       name, group_count, default_group_name, next_year_, 12, 31,
       &default_group_number);
   int winner_index(-2);
   std::string winner_name;
 
   for (int i = 1; i <= group_count; ++i) {
-    int might_win = trial->AppendGroup("", 1);
+    int might_win = trial->AppendGroup(std::string(), 1);
 
     // Because we keep appending groups, we want to see if the last group that
     // was added has been assigned or not.
     if (trial->group_ == might_win) {
       EXPECT_EQ(-2, winner_index);
       winner_index = might_win;
       StringAppendF(&winner_name, "%d", might_win);
       EXPECT_EQ(winner_name, trial->group_name());
     }
   }
@@ skipping 602 matching lines @@
 
   FieldTrial* trial =
       FieldTrialList::FactoryGetFieldTrial(
           kTrialName, kProbability, kDefaultGroupName,
           FieldTrialList::kNoExpirationYear, 1, 1, NULL);
   trial->AppendGroup(kGroupName, kProbability);
   EXPECT_EQ(kGroupName, trial->group_name());
 }
 
 }  // namespace base