Generate build timing metrics to proto format file

Test: Dumped the text formated based metrics file to out dir,
and checked the file.
Bug: b/63815990

Change-Id: Iff476f72a0be74eb53b6b26ef468d11c0f24a404

ui/build/dumpvars.go

@@ -19,6 +19,7 @@ import (
 	"fmt"
 	"strings"
 
+	"android/soong/ui/metrics"
 	"android/soong/ui/status"
 )
 
@@ -69,7 +70,7 @@ func DumpMakeVars(ctx Context, config Config, goals, vars []string) (map[string]
 }
 
 func dumpMakeVars(ctx Context, config Config, goals, vars []string, write_soong_vars bool) (map[string]string, error) {
-	ctx.BeginTrace("dumpvars")
+	ctx.BeginTrace(metrics.RunKati, "dumpvars")
 	defer ctx.EndTrace()
 
 	cmd := Command(ctx, config, "dumpvars",
@@ -113,6 +114,9 @@ func dumpMakeVars(ctx Context, config Config, goals, vars []string, write_soong_
 			return nil, fmt.Errorf("Failed to parse make line: %q", line)
 		}
 	}
+	if ctx.Metrics != nil {
+		ctx.Metrics.SetMetadataMetrics(ret)
+	}
 
 	return ret, nil
 }