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

chrome/test/ui/ui_test.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/test/ui/ui_test.h"
 
 #if defined(OS_POSIX)
 #include <signal.h>
 #include <sys/types.h>
 #endif
@@ skipping 498 matching lines @@
   launch_arguments_.AppendSwitchASCII(name, value);
 }
 
 bool UITestBase::BeginTracing(const std::string& categories) {
   return automation()->BeginTracing(categories);
 }
 
 std::string UITestBase::EndTracing() {
   std::string json_trace_output;
   if (!automation()->EndTracing(&json_trace_output))
-    return "";
+    return std::string();
   return json_trace_output;
 }
 
 // UITest methods
 
 void UITest::SetUp() {
   // Pass the test case name to chrome.exe on the command line to help with
   // parsing Purify output.
   const testing::TestInfo* const test_info =
       testing::UnitTest::GetInstance()->current_test_info();
@@ skipping 191 matching lines @@
   ASSERT_TRUE(session_end_completed);
 
   // Make sure session restore says we didn't crash.
   scoped_ptr<DictionaryValue> profile_prefs(GetDefaultProfilePreferences());
   ASSERT_TRUE(profile_prefs.get());
   std::string exit_type;
   ASSERT_TRUE(profile_prefs->GetString(prefs::kSessionExitedCleanly,
                                         &exit_type));
   EXPECT_EQ(ProfileImpl::kPrefExitTypeNormal, exit_type);
 }