Use a direct include of strings headers in chrome/common/, part 1.

chrome/common/cloud_print/cloud_print_helpers_unittest.cc

 // Copyright 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/common/cloud_print/cloud_print_helpers.h"
 
 #include "base/md5.h"
-#include "base/stringprintf.h"
+#include "base/strings/stringprintf.h"
 #include "base/sys_info.h"
 #include "chrome/common/chrome_version_info.h"
 #include "googleurl/src/gurl.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace cloud_print {
 
 namespace {
 
 void CheckURLs(const GURL& server_base_url) {
@@ skipping 104 matching lines @@
       std::string("__test__tagshash")));
 }
 
 TEST(CloudPrintHelpersTest, GetCloudPrintAuthHeader) {
   std::string test_auth("testauth");
   EXPECT_EQ("Authorization: OAuth testauth",
             GetCloudPrintAuthHeader(test_auth));
 }
 
 }  // namespace cloud_print