Extend memory usage events to report mapped memory usage.

PiperOrigin-RevId: 212887555
Change-Id: I3545383ce903cbe9f00d9b5288d9ef9a049b9f4f

pkg/sentry/kernel/memevent/memory_events.go

@@ -94,5 +94,8 @@ func (m *MemoryEvents) emit() {
 	snapshot, _ := usage.MemoryAccounting.Copy()
 	total := totalPlatform + snapshot.Mapped
 
-	eventchannel.Emit(&pb.MemoryUsageEvent{Total: total})
+	eventchannel.Emit(&pb.MemoryUsageEvent{
+		Mapped: snapshot.Mapped,
+		Total:  total,
+	})
 }

pkg/sentry/kernel/memevent/memory_events.proto

@@ -22,4 +22,8 @@ message MemoryUsageEvent {
   // The total memory usage of the sandboxed application in bytes, calculated
   // using the 'fast' method.
   uint64 total = 1;
+
+  // Memory used to back memory-mapped regions for files in the application, in
+  // bytes. This corresponds to the usage.MemoryKind.Mapped memory type.
+  uint64 mapped = 2;
 }