Add "create_bundle" target in order to support bundle with gn.

tools/gn/ninja_target_writer.cc

Index: tools/gn/ninja_target_writer.cc
diff --git a/tools/gn/ninja_target_writer.cc b/tools/gn/ninja_target_writer.cc
index f4de7f2247b8803c48092d91c5f761acad03e6ed..486930bd2ffeb224f6985d16860ee42c2431a8ce 100644
--- a/tools/gn/ninja_target_writer.cc
+++ b/tools/gn/ninja_target_writer.cc
@@ -15,6 +15,7 @@
 #include "tools/gn/ninja_binary_target_writer.h"
 #include "tools/gn/ninja_bundle_data_target_writer.h"
 #include "tools/gn/ninja_copy_target_writer.h"
+#include "tools/gn/ninja_create_bundle_target_writer.h"
 #include "tools/gn/ninja_group_target_writer.h"
 #include "tools/gn/ninja_utils.h"
 #include "tools/gn/output_file.h"
@@ -61,6 +62,9 @@ void NinjaTargetWriter::RunAndWriteFile(const Target* target) {
   if (target->output_type() == Target::BUNDLE_DATA) {
     NinjaBundleDataTargetWriter writer(target, file);
     writer.Run();
+  } else if (target->output_type() == Target::CREATE_BUNDLE) {
+    NinjaCreateBundleTargetWriter writer(target, file);
+    writer.Run();
   } else if (target->output_type() == Target::COPY_FILES) {
     NinjaCopyTargetWriter writer(target, file);
     writer.Run();