Added HistoryService::GetHistoryCount() and helper functions in components/history

components/history/core/browser/history_backend.cc

Index: components/history/core/browser/history_backend.cc
diff --git a/components/history/core/browser/history_backend.cc b/components/history/core/browser/history_backend.cc
index 8e4cfaaf74944b0e1a3ca9a134fba7ddd0b29c35..a381efa5ff4326eb2d5b85dadab3acff0f00756e 100644
--- a/components/history/core/browser/history_backend.cc
+++ b/components/history/core/browser/history_backend.cc
@@ -1054,6 +1054,15 @@ TypedUrlSyncableService* HistoryBackend::GetTypedUrlSyncableService() const {
   return typed_url_syncable_service_.get();
 }
 
+// Statistics ------------------------------------------------------------------
+
+HistoryCountResult HistoryBackend::GetHistoryCount() {
+  HistoryCountResult result;
+  result.count = 0;
+  result.success = db_ && db_->GetHistoryCount(&result.count);
+  return result;
+}
+
 // Keyword visits --------------------------------------------------------------
 
 void HistoryBackend::SetKeywordSearchTermsForURL(const GURL& url,