Fix a bug where the minimum granular time for Alarms was not calculated properly.

chrome/browser/extensions/api/alarms/alarm_manager.h

Index: chrome/browser/extensions/api/alarms/alarm_manager.h
diff --git a/chrome/browser/extensions/api/alarms/alarm_manager.h b/chrome/browser/extensions/api/alarms/alarm_manager.h
index 3f92db8dcef53cd1e293a87a9030ad62dcf5ae98..a0e3b7f30bb9ea011c218717ea8095f61b63aaff 100644
--- a/chrome/browser/extensions/api/alarms/alarm_manager.h
+++ b/chrome/browser/extensions/api/alarms/alarm_manager.h
@@ -44,6 +44,9 @@ struct Alarm {
   // time.  This will always be at least as large as the min_granularity
   // constructor argument.
   base::TimeDelta granularity;
+  // The minimum granularity is the minimum allowed polling rate. This stops
+  // alarms from polling too often.
+  base::TimeDelta minimum_granularity;
 };
 
 // Manages the currently pending alarms for every extension in a profile.