wspr: Change vtrace to use the vdl time package.

Also change from using a TraceMethod to having TraceFlags.  This
will make it easier to add new features like log levels.

MultiPart: 2/3
Change-Id: Ice2a5ae6af4c408160fb8c214d8462635fd0fe69
diff --git a/services/wsprd/app/app.go b/services/wsprd/app/app.go
index 1b69988..0b0197a 100644
--- a/services/wsprd/app/app.go
+++ b/services/wsprd/app/app.go
@@ -205,8 +205,8 @@
 	response := VeyronRPCResponse{
 		OutArgs: outargs,
 		TraceResponse: vtrace.Response{
-			Method: vtrace.InMemory,
-			Trace:  *traceRecord,
+			Flags: vtrace.CollectInMemory,
+			Trace: *traceRecord,
 		},
 	}
 	encoded, err := lib.VomEncode(response)
diff --git a/services/wsprd/app/app_test.go b/services/wsprd/app/app_test.go
index db3986c..a794b94 100644
--- a/services/wsprd/app/app_test.go
+++ b/services/wsprd/app/app_test.go
@@ -249,7 +249,7 @@
 	return lib.VomEncodeOrDie(VeyronRPCResponse{
 		OutArgs: outArgs,
 		TraceResponse: vtrace.Response{
-			Method: vtrace.InMemory,
+			Flags: vtrace.CollectInMemory,
 		},
 	})
 }