Fix some AppCompacted proto nits post google3 review.

Clarify some comments and tweak the names of some fields. Binary
structure of the proto remains intact.

Bug: 119988524
Bug: 120600464

Test: verified that statsd_testdrive still works with this atom
Change-Id: I90d8eb522fc23b2ff604bc1e69e4068dc2c4b73a
diff --git a/cmds/statsd/src/atoms.proto b/cmds/statsd/src/atoms.proto
index 0c05be1..bdcdc536 100644
--- a/cmds/statsd/src/atoms.proto
+++ b/cmds/statsd/src/atoms.proto
@@ -3670,7 +3670,7 @@
     SOME = 1;
     FULL = 2;
   }
-  optional Action action = 3 [default = UNKNOWN];
+  optional Action action = 3;
 
   // Total RSS in kilobytes consumed by the process prior to compaction.
   optional int64 before_rss_total_kilobytes = 4;
@@ -3702,12 +3702,12 @@
   // The last compaction action performed for this app.
   optional Action last_action = 13;
 
-  // The last time that compaction was attempted on this process in seconds
-  // since boot.
-  optional int64 last_compact_timestamp = 14;
+  // The last time that compaction was attempted on this process in milliseconds
+  // since boot, not including sleep (see SystemClock.uptimeMillis()).
+  optional int64 last_compact_timestamp_ms_since_boot = 14;
 
-  // The oom_adj at the time of compaction.
-  optional int32 oom_adj = 15;
+  // The oom_score_adj at the time of compaction.
+  optional int32 oom_score_adj = 15;
 
   // The process state at the time of compaction.
   optional android.app.ProcessStateEnum process_state = 16 [default = PROCESS_STATE_UNKNOWN];