add a couple of casts.

components/offline_pages/offline_page_metadata_store_sql.cc

 // Copyright 2016 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/offline_pages/offline_page_metadata_store_sql.h"
 
 #include "base/bind.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/location.h"
@@ skipping 257 matching lines @@
 
 void OfflinePageMetadataStoreSQL::NotifyLoadResult(
     scoped_refptr<base::SingleThreadTaskRunner> runner,
     const LoadCallback& callback,
     LoadStatus status,
     const std::vector<OfflinePageItem>& result) {
   // TODO(bburns): Switch to SQL specific UMA metrics.
   UMA_HISTOGRAM_ENUMERATION("OfflinePages.LoadStatus", status,
                             OfflinePageMetadataStore::LOAD_STATUS_COUNT);
   if (status == LOAD_SUCCEEDED) {
-    UMA_HISTOGRAM_COUNTS("OfflinePages.SavedPageCount", result.size());
+    UMA_HISTOGRAM_COUNTS("OfflinePages.SavedPageCount",
+                         static_cast<int32_t>(result.size()));
   } else {
     DVLOG(1) << "Offline pages database loading failed: " << status;
   }
   runner->PostTask(FROM_HERE, base::Bind(callback, status, result));
 }
 
 void OfflinePageMetadataStoreSQL::Load(const LoadCallback& callback) {
   db_.reset(new sql::Connection());
   background_task_runner_->PostTask(
       FROM_HERE,
@@ skipping 33 matching lines @@
 }
 
 void OfflinePageMetadataStoreSQL::Reset(const ResetCallback& callback) {
   background_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&OfflinePageMetadataStoreSQL::ResetSync, base::Passed(&db_),
                  base::ThreadTaskRunnerHandle::Get(), callback));
 }
 
 }  // namespace offline_pages