Change uses of base::JoinString to pass StringPieces where possible.

chrome/browser/chrome_browser_main.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/browser/chrome_browser_main.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <set>
@@ skipping 13 matching lines @@
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/path_service.h"
 #include "base/profiler/scoped_tracker.h"
 #include "base/profiler/stack_sampling_profiler.h"
 #include "base/run_loop.h"
 #include "base/strings/string16.h"
 #include "base/strings/string_number_conversions.h"
+#include "base/strings/string_piece.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/sys_info.h"
 #include "base/threading/platform_thread.h"
 #include "base/time/default_tick_clock.h"
 #include "base/time/time.h"
 #include "base/trace_event/trace_event.h"
 #include "base/values.h"
 #include "build/build_config.h"
 #include "cc/base/switches.h"
@@ skipping 802 matching lines @@
     if (!new_public_key.empty()) {
       command_line->AppendSwitchASCII(
           switches::kOriginTrialPublicKey,
           local_state_->GetString(prefs::kOriginTrialPublicKey));
     }
   }
   if (!command_line->HasSwitch(switches::kOriginTrialDisabledFeatures)) {
     const base::ListValue* override_disabled_feature_list =
         local_state_->GetList(prefs::kOriginTrialDisabledFeatures);
     if (override_disabled_feature_list) {
-      std::vector<std::string> disabled_features;
-      std::string disabled_feature;
+      std::vector<base::StringPiece> disabled_features;
+      base::StringPiece disabled_feature;
       for (const auto& item : *override_disabled_feature_list) {
         if (item->GetAsString(&disabled_feature)) {
           disabled_features.push_back(disabled_feature);
         }
       }
       if (!disabled_features.empty()) {
         const std::string override_disabled_features =
             base::JoinString(disabled_features, "|");
         command_line->AppendSwitchASCII(switches::kOriginTrialDisabledFeatures,
                                         override_disabled_features);
@@ skipping 1218 matching lines @@
   chromeos::CrosSettings::Shutdown();
 #endif  // defined(OS_CHROMEOS)
 #endif  // defined(OS_ANDROID)
 }
 
 // Public members:
 
 void ChromeBrowserMainParts::AddParts(ChromeBrowserMainExtraParts* parts) {
   chrome_extra_parts_.push_back(parts);
 }