Refactor cache counting into a separate helper class

chrome/browser/browsing_data/conditional_cache_deletion_helper_browsertest.cc

 // Copyright (c) 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 <algorithm>
 #include <memory>
 #include <set>
 #include <string>
 #include <vector>
 
@@ skipping 127 matching lines @@
     int pos = 0;
     for (const std::string& key : keys) {
       WaitForCompletion(backend_->CreateEntry(
           key, &entries_[pos++], done_callback_));
     }
   }
 
   void DeleteEntries(
       const base::Callback<bool(const disk_cache::Entry*)>& condition) {
     DCHECK_CURRENTLY_ON(BrowserThread::IO);
-    ConditionalCacheDeletionHelper* helper = new ConditionalCacheDeletionHelper(
-        backend_,
-        condition);
+    auto* helper = new ConditionalCacheDeletionHelper(backend_, condition);
 
     WaitForCompletion(helper->DeleteAndDestroySelfWhenFinished(done_callback_));
   }
 
   void GetRemainingKeys() {
     DCHECK_CURRENTLY_ON(BrowserThread::IO);
     current_entry_ = nullptr;
     iterator_ = backend_->CreateIterator();
     GetNextKey(net::OK);
   }
@@ skipping 37 matching lines @@
   std::unique_ptr<base::WaitableEvent> waitable_event_;
   int remaining_tasks_;
 
   std::vector<std::string> remaining_keys_;
 };
 
 // Tests that ConditionalCacheDeletionHelper only deletes those cache entries
 // that match the condition.
 IN_PROC_BROWSER_TEST_F(ConditionalCacheDeletionHelperBrowserTest, Condition) {
   // Create 5 entries.
-  std::set<std::string> keys;
-  keys.insert("123");
-  keys.insert("47");
-  keys.insert("56");
-  keys.insert("81");
-  keys.insert("42");
+  std::set<std::string> keys = {"123", "47", "56", "81", "42"};
 
   BrowserThread::PostTask(
       BrowserThread::IO, FROM_HERE,
       base::Bind(&ConditionalCacheDeletionHelperBrowserTest::CreateCacheEntries,
                  base::Unretained(this),
                  base::ConstRef(keys)));
   WaitForTasksOnIOThread();
 
   // Delete the entries whose keys are even numbers.
   BrowserThread::PostTask(
@@ skipping 85 matching lines @@
       BrowserThread::IO, FROM_HERE,
       base::Bind(&ConditionalCacheDeletionHelperBrowserTest::GetRemainingKeys,
                  base::Unretained(this)));
   WaitForTasksOnIOThread();
 
   keys.insert(newer_keys.begin(), newer_keys.end());
   keys.erase("https://example.com/foo/bar/icon2.png");
   keys.erase("https://example.com/foo/bar/icon3.png");
   CompareRemainingKeys(keys);
 }