Log app and tab discards.

components/device_event_log/device_event_log.h

Index: components/device_event_log/device_event_log.h
diff --git a/components/device_event_log/device_event_log.h b/components/device_event_log/device_event_log.h
index be9411b0106317526db4ecc5195fe1a50d6955c1..133cf794b949004a66803af61cf60bbd4ad4745d 100644
--- a/components/device_event_log/device_event_log.h
+++ b/components/device_event_log/device_event_log.h
@@ -57,6 +57,9 @@
 #define HID_PLOG(level)                         \
   DEVICE_PLOG(::device_event_log::LOG_TYPE_HID, \
               ::device_event_log::LOG_LEVEL_##level)
+#define MEMORY_LOG(level)                         \
+  DEVICE_LOG(::device_event_log::LOG_TYPE_MEMORY, \
+             ::device_event_log::LOG_LEVEL_##level)
 
 // Generally prefer the above macros unless |type| or |level| is not constant.
 
@@ -96,8 +99,10 @@ enum LogType {
   LOG_TYPE_USB = 4,
   // Human-interface device related events (i.e. device/hid).
   LOG_TYPE_HID = 5,
+  // Memory related events.
+  LOG_TYPE_MEMORY = 6,
   // Used internally, must be the last type (may be changed).
-  LOG_TYPE_UNKNOWN = 6
+  LOG_TYPE_UNKNOWN = 7
 };
 
 // Used to specify the detail level for logging. In GetAsString, used to