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

base/feature_list.cc

 // Copyright 2015 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/feature_list.h"
 
 #include <stddef.h>
 
 #include <utility>
 #include <vector>
@@ skipping 210 matching lines @@
   }
   return g_instance->IsFeatureEnabled(feature);
 }
 
 // static
 FieldTrial* FeatureList::GetFieldTrial(const Feature& feature) {
   return GetInstance()->GetAssociatedFieldTrial(feature);
 }
 
 // static
-std::vector<std::string> FeatureList::SplitFeatureListString(
-    const std::string& input) {
-  return SplitString(input, ",", TRIM_WHITESPACE, SPLIT_WANT_NONEMPTY);
+std::vector<base::StringPiece> FeatureList::SplitFeatureListString(
+    base::StringPiece input) {
+  return SplitStringPiece(input, ",", TRIM_WHITESPACE, SPLIT_WANT_NONEMPTY);
 }
 
 // static
 bool FeatureList::InitializeInstance(const std::string& enable_features,
                                      const std::string& disable_features) {
   // We want to initialize a new instance here to support command-line features
   // in testing better. For example, we initialize a dummy instance in
   // base/test/test_suite.cc, and override it in content/browser/
   // browser_main_loop.cc.
   // On the other hand, we want to avoid re-initialization from command line.
@@ skipping 89 matching lines @@
     return entry.field_trial;
   }
 
   return nullptr;
 }
 
 void FeatureList::RegisterOverridesFromCommandLine(
     const std::string& feature_list,
     OverrideState overridden_state) {
   for (const auto& value : SplitFeatureListString(feature_list)) {
-    StringPiece feature_name(value);
+    StringPiece feature_name = value;
     base::FieldTrial* trial = nullptr;
 
     // The entry may be of the form FeatureName<FieldTrialName - in which case,
     // this splits off the field trial name and associates it with the override.
     std::string::size_type pos = feature_name.find('<');
     if (pos != std::string::npos) {
       feature_name.set(value.data(), pos);
-      trial = base::FieldTrialList::Find(value.substr(pos + 1));
+      trial = base::FieldTrialList::Find(value.substr(pos + 1).as_string());
     }
 
     RegisterOverride(feature_name, overridden_state, trial);
   }
 }
 
 void FeatureList::RegisterOverride(StringPiece feature_name,
                                    OverrideState overridden_state,
                                    FieldTrial* field_trial) {
   DCHECK(!initialized_);
@@ skipping 26 matching lines @@
   return it->second == &feature;
 }
 
 FeatureList::OverrideEntry::OverrideEntry(OverrideState overridden_state,
                                           FieldTrial* field_trial)
     : overridden_state(overridden_state),
       field_trial(field_trial),
       overridden_by_field_trial(field_trial != nullptr) {}
 
 }  // namespace base