Account for internal actions in stats summary.

RELNOTES: None

Closes #11896.

PiperOrigin-RevId: 330509808
diff --git a/src/main/java/com/google/devtools/build/lib/runtime/BuildSummaryStatsModule.java b/src/main/java/com/google/devtools/build/lib/runtime/BuildSummaryStatsModule.java
index 496754e..b7eaaf1 100644
--- a/src/main/java/com/google/devtools/build/lib/runtime/BuildSummaryStatsModule.java
+++ b/src/main/java/com/google/devtools/build/lib/runtime/BuildSummaryStatsModule.java
@@ -18,6 +18,7 @@
 import com.google.common.eventbus.EventBus;
 import com.google.common.eventbus.Subscribe;
 import com.google.common.flogger.GoogleLogger;
+import com.google.devtools.build.lib.actions.ActionCompletionEvent;
 import com.google.devtools.build.lib.actions.ActionKeyContext;
 import com.google.devtools.build.lib.actions.ActionResultReceivedEvent;
 import com.google.devtools.build.lib.buildtool.BuildRequest;
@@ -110,6 +111,12 @@
   }
 
   @Subscribe
+  @AllowConcurrentEvents
+  public void actionCompletion(ActionCompletionEvent event) {
+    spawnStats.incrementActionCount();
+  }
+
+  @Subscribe
   public void buildComplete(BuildCompleteEvent event) {
     try {
       // We might want to make this conditional on a flag; it can sometimes be a bit of a nuisance.