Add FilterListPred.

Test: cd build/soong; go test ./android
Change-Id: Ibbdd3cbdb822bd2e843096a22cdd08c827b70526

android/util_test.go

@@ -18,6 +18,7 @@ import (
 	"fmt"
 	"reflect"
 	"strconv"
+	"strings"
 	"testing"
 )
 
@@ -299,6 +300,14 @@ func TestFilterList(t *testing.T) {
 	}
 }
 
+func TestFilterListPred(t *testing.T) {
+	pred := func(s string) bool { return strings.HasPrefix(s, "a/") }
+	AssertArrayString(t, "filter", FilterListPred([]string{"a/c", "b/a", "a/b"}, pred), []string{"a/c", "a/b"})
+	AssertArrayString(t, "filter", FilterListPred([]string{"b/c", "a/a", "b/b"}, pred), []string{"a/a"})
+	AssertArrayString(t, "filter", FilterListPred([]string{"c/c", "b/a", "c/b"}, pred), []string{})
+	AssertArrayString(t, "filter", FilterListPred([]string{"a/c", "a/a", "a/b"}, pred), []string{"a/c", "a/a", "a/b"})
+}
+
 func TestRemoveListFromList(t *testing.T) {
 	input := []string{"a", "b", "c", "d", "a", "c", "d"}
 	filter := []string{"a", "c"}