[Downloads] Remove unmapped histograms.

components/history/core/browser/history_backend.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 "components/history/core/browser/history_backend.h"
 
 #include <algorithm>
 #include <functional>
 #include <list>
 #include <map>
@@ skipping 1203 matching lines @@
   size_t num_downloads_deleted = downloads_count_before - downloads_count_after;
   UMA_HISTOGRAM_COUNTS("Download.DatabaseRemoveDownloadsCount",
                        num_downloads_deleted);
   base::TimeDelta micros = (1000 * (finished_removing - started_removing));
   UMA_HISTOGRAM_TIMES("Download.DatabaseRemoveDownloadsTime", micros);
   if (num_downloads_deleted > 0) {
     UMA_HISTOGRAM_TIMES("Download.DatabaseRemoveDownloadsTimePerRecord",
                         (1000 * micros) / num_downloads_deleted);
   }
   DCHECK_GE(ids.size(), num_downloads_deleted);
-  if (ids.size() < num_downloads_deleted)
-    return;
-  UMA_HISTOGRAM_COUNTS("Download.DatabaseRemoveDownloadsCountNotRemoved",
-                       ids.size() - num_downloads_deleted);
 }
 
 void HistoryBackend::QueryHistory(const base::string16& text_query,
                                   const QueryOptions& options,
                                   QueryResults* query_results) {
   DCHECK(query_results);
   base::TimeTicks beginning_time = base::TimeTicks::Now();
   if (db_) {
     if (text_query.empty()) {
       // Basic history query for the main database.
@@ skipping 1408 matching lines @@
   // transaction is currently open.
   db_->CommitTransaction();
   db_->Vacuum();
   db_->BeginTransaction();
   db_->GetStartDate(&first_recorded_time_);
 
   return true;
 }
 
 }  // namespace history