add a couple of casts.

components/offline_pages/offline_page_metadata_store_sql.cc

Index: components/offline_pages/offline_page_metadata_store_sql.cc
diff --git a/components/offline_pages/offline_page_metadata_store_sql.cc b/components/offline_pages/offline_page_metadata_store_sql.cc
index 8a7686f2c0c30266c6665cd71acd77da9104c655..095d923b26c2046d29d055e32fd25c9df8032f9e 100644
--- a/components/offline_pages/offline_page_metadata_store_sql.cc
+++ b/components/offline_pages/offline_page_metadata_store_sql.cc
@@ -275,7 +275,8 @@ void OfflinePageMetadataStoreSQL::NotifyLoadResult(
   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;
   }