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

content/browser/download/download_stats.h

Index: content/browser/download/download_stats.h
diff --git a/content/browser/download/download_stats.h b/content/browser/download/download_stats.h
index cd98d7a48dc22bdd8253ceede043a9b5462df5a5..a0ffd28df8ca3b8de3105b9ce961b20b589dfc3a 100644
--- a/content/browser/download/download_stats.h
+++ b/content/browser/download/download_stats.h
@@ -14,6 +14,7 @@
 #include "content/common/content_export.h"
 
 namespace base {
+class Time;
 class TimeTicks;
 }
 
@@ -88,6 +89,23 @@ void RecordDownloadWriteSize(size_t data_len);
 // Record WRITE_LOOP_COUNT and number of loops.
 void RecordDownloadWriteLoopCount(int count);
 
+// Record the time of both the first open and all subsequent opens since the
+// download completed.
+void RecordOpen(const base::Time& end, bool first);
+
+// Record the number of items loaded from the history db.
+void RecordHistorySize(int size);
+
+// Record the number of items that are in the history at the time that a
+// new download begins.
+void RecordHistorySize2(int size);
+
+// Record the number of items showing in the shelf when it closes.
+void RecordShelfSize(int size);
+
+// Record the number of downloads removed by ClearAll.
+void RecordClearAllSize(int size);
+
 }  // namespace download_stats
 
 #endif  // CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_STATS_H_