Add new UMA stats to get a handle on Downloads UI Usage

chrome/browser/history/history_types.h

Index: chrome/browser/history/history_types.h
diff --git a/chrome/browser/history/history_types.h b/chrome/browser/history/history_types.h
index ff4741d8c0525f4dba26e65d55a7fff8e4c3676c..b8598d4a21c3eb98ed6f826b24d45dbd40016578 100644
--- a/chrome/browser/history/history_types.h
+++ b/chrome/browser/history/history_types.h
@@ -739,6 +739,20 @@ struct FaviconData {
   history::IconType icon_type;
 };
 
+// The DownloadItem fields that are persisted and may change, which is a subset
+// of DownloadPersistentStoreInfo.
+// TODO(benjhayden): Add filepath and unify UpdateDownload{,Path}().
+struct DownloadItemData {
+  DownloadItemData();
+  ~DownloadItemData();
+
+  int64 received_bytes;
+  int32 state;
+  base::Time end_time;
+  bool opened;
+  DownloadID db_handle;
+};
+
 }  // namespace history
 
 #endif  // CHROME_BROWSER_HISTORY_HISTORY_TYPES_H_