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 6e55d07fc2df109340ff36ed096853187d546543..bfb244c8e099d3831b768831072f9e6b8b45cb30 100644
--- a/content/browser/download/download_stats.h
+++ b/content/browser/download/download_stats.h
@@ -15,6 +15,7 @@
 #include "content/browser/download/interrupt_reasons.h"
 
 namespace base {
+class Time;
 class TimeTicks;
 }
 
@@ -91,6 +92,25 @@ 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 that are in the history at the time that a
+// new download is added to the history.
+void RecordHistorySize(int size);
+
+// Record the total number of items and the number of in-progress items showing
+// in the shelf when it closes.  Set |autoclose| to true when the shelf is
+// closing itself, false when the user explicitly closed it.
+void RecordShelfClose(int size, int in_progress, bool autoclose);
+
+// Record the number of downloads removed by ClearAll.
+void RecordClearAllSize(int size);
+
+// Record the number of completed unopened downloads when a download is opened.
+void RecordOpensOutstanding(int size);
+
 }  // namespace download_stats
 
 #endif  // CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_STATS_H_