[fuchsia importer] Import async events from Fuchsia traces

Also updates the existing slices smoke test to separate the slice counts
by both ref_type and depth.

Change-Id: I0dc544b6f04028e861e5f534f9efa7facb7b6449
diff --git a/test/trace_processor/index b/test/trace_processor/index
index ab34397..d998e62 100644
--- a/test/trace_processor/index
+++ b/test/trace_processor/index
@@ -7,6 +7,7 @@
 ../data/fuchsia_trace.fxt smoke_slices.sql fuchsia_smoke_slices.out
 ../data/fuchsia_trace.fxt smoke_instants.sql fuchsia_smoke_instants.out
 ../data/fuchsia_trace.fxt smoke_counters.sql fuchsia_smoke_counters.out
+../data/fuchsia_workstation.fxt smoke_slices.sql fuchsia_workstation_smoke_slices.out
 
 # Test for the process<>thread tracking logic.
 synth_process_tracking.py process_tracking.sql process_tracking.out