Remove EmptyRuleIterators with nullptrs.

components/content_settings/core/browser/content_settings_rule.cc

 // Copyright (c) 2011 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 "components/content_settings/core/browser/content_settings_rule.h"
+
+#include <utility>
+
 #include "base/logging.h"
-#include "components/content_settings/core/browser/content_settings_rule.h"
 
 namespace content_settings {
 
 Rule::Rule() {}
 
 Rule::Rule(
     const ContentSettingsPattern& primary_pattern,
     const ContentSettingsPattern& secondary_pattern,
     base::Value* value)
     : primary_pattern(primary_pattern),
       secondary_pattern(secondary_pattern),
       value(value) {
   DCHECK(value);
 }
 
 Rule::Rule(const Rule& other) = default;
 
 Rule::~Rule() {}
 
 RuleIterator::~RuleIterator() {}
 
-EmptyRuleIterator::~EmptyRuleIterator() {}
-
-bool EmptyRuleIterator::HasNext() const {
-  return false;
-}
-
-Rule EmptyRuleIterator::Next() {
-  NOTREACHED();
-  return Rule();
-}
-
 ConcatenationIterator::ConcatenationIterator(
     std::vector<std::unique_ptr<RuleIterator>> iterators,
     base::AutoLock* auto_lock)
     : iterators_(std::move(iterators)), auto_lock_(auto_lock) {
   auto it = iterators_.begin();
   while (it != iterators_.end()) {
     if (!(*it)->HasNext())
       it = iterators_.erase(it);
     else
       ++it;
   }
 }
 
 ConcatenationIterator::~ConcatenationIterator() {}
 
 bool ConcatenationIterator::HasNext() const {
-  return (!iterators_.empty());
+  return !iterators_.empty();
 }
 
 Rule ConcatenationIterator::Next() {
   auto current_iterator = iterators_.begin();
   DCHECK(current_iterator != iterators_.end());
   DCHECK((*current_iterator)->HasNext());
   const Rule& to_return = (*current_iterator)->Next();
   if (!(*current_iterator)->HasNext())
     iterators_.erase(current_iterator);
   return to_return;
 }
 
 }  // namespace content_settings