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

tools/gn/target_generator.cc

Index: tools/gn/target_generator.cc
diff --git a/tools/gn/target_generator.cc b/tools/gn/target_generator.cc
index 0a833a02ca386c79c19cbf21082ef82cd6ecac23..76fcb533cf5b84f9182dd52d62267612316d2aea 100644
--- a/tools/gn/target_generator.cc
+++ b/tools/gn/target_generator.cc
@@ -12,6 +12,7 @@
 #include "tools/gn/bundle_data_target_generator.h"
 #include "tools/gn/config.h"
 #include "tools/gn/copy_target_generator.h"
+#include "tools/gn/create_bundle_target_generator.h"
 #include "tools/gn/err.h"
 #include "tools/gn/filesystem_utils.h"
 #include "tools/gn/functions.h"
@@ -92,6 +93,10 @@ void TargetGenerator::GenerateTarget(Scope* scope,
     BundleDataTargetGenerator generator(
         target.get(), scope, function_call, err);
     generator.Run();
+  } else if (output_type == functions::kCreateBundle) {
+    CreateBundleTargetGenerator generator(
+        target.get(), scope, function_call, err);
+    generator.Run();
   } else if (output_type == functions::kCopy) {
     CopyTargetGenerator generator(target.get(), scope, function_call, err);
     generator.Run();