base: Get rid of 'using' declaration of StringAppendF.

chrome/test/tab_switching/tab_switching_test.cc

 // Copyright (c) 2010 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/command_line.h"
 #include "base/environment.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/path_service.h"
 #include "base/platform_thread.h"
@@ skipping 48 matching lines @@
     // Run the rest of the UITest initialization.
     UITest::SetUp();
   }
 
   static const int kNumCycles = 5;
 
   void PrintTimings(const char* label, TimeDelta timings[kNumCycles],
     bool important) {
       std::string times;
       for (int i = 0; i < kNumCycles; ++i)
-        StringAppendF(&times, "%.2f,", timings[i].InMillisecondsF());
+        base::StringAppendF(&times, "%.2f,", timings[i].InMillisecondsF());
       PrintResultList("times", "", label, times, "ms", important);
   }
 
   void RunTabSwitchingUITest(const char* label, bool important) {
     // Shut down from window UITest sets up automatically.
     UITest::TearDown();
 
     TimeDelta timings[kNumCycles];
     for (int i = 0; i < kNumCycles; ++i) {
       // Prepare for this test run.
@@ skipping 106 matching lines @@
 TEST_F(TabSwitchingUITest, TabSwitch) {
   RunTabSwitchingUITest("t", true);
 }
 
 TEST_F(TabSwitchingUITest, TabSwitchRef) {
   UseReferenceBuild();
   RunTabSwitchingUITest("t_ref", true);
 }
 
 }  // namespace