always emit Page.setDownloadBehavior for now

For this, I needed to teach the tool to obey AlwaysEmit for commands as
well. The existing fixup functions weren't enough for this change
either, as they run after we've removed deprecated commands and types in
the cleanup stage.

Fixes chromedp/chromedp#627.

main.go

@@ -192,13 +192,24 @@ func run() error {
 		// skip if not processing
 		if d.Deprecated {
 			var extra []string
-			if d.Deprecated {
-				extra = append(extra, "deprecated")
-			}
+			extra = append(extra, "deprecated")
 			util.Logf("SKIPPING(%s): %s %v", pad("domain", 7), d.Domain.String(), extra)
 			continue
 		}
 
+		// TODO: remove this pre-cleanup fixup at some point; right now,
+		// it's necessary as the current Chrome stable release doesn't
+		// yet support the new Browser.setDownloadBehavior.
+		switch d.Domain {
+		case "Page":
+			for _, c := range d.Commands {
+				switch c.Name {
+				case "setDownloadBehavior":
+					c.AlwaysEmit = true
+				}
+			}
+		}
+
 		// will process
 		pkgs = append(pkgs, genutil.PackageName(d))
 		processed = append(processed, d)
@@ -337,12 +348,12 @@ func cleanupTypes(n string, dtyp string, typs []*pdl.Type) []*pdl.Type {
 
 	for _, t := range typs {
 		typ := dtyp + "." + t.Name
-		if t.Deprecated {
+		if t.Deprecated && !t.AlwaysEmit {
 			util.Logf("SKIPPING(%s): %s [deprecated]", pad(n, 7), typ)
 			continue
 		}
 
-		if t.Redirect != nil {
+		if t.Redirect != nil && !t.AlwaysEmit {
 			util.Logf("SKIPPING(%s): %s [redirect:%s]", pad(n, 7), typ, t.Redirect)
 			continue
 		}