Generate all extension schema namespaces as "api" and instead vary the generated bundle names.

extensions/browser/api/cast_channel/cast_framer.h

Index: extensions/browser/api/cast_channel/cast_framer.h
diff --git a/extensions/browser/api/cast_channel/cast_framer.h b/extensions/browser/api/cast_channel/cast_framer.h
index 3d899146947dd7db92b2f3812ef8e4d454ec5392..81c9f90792bced1449ab2ff932d1671f622c4ff8 100644
--- a/extensions/browser/api/cast_channel/cast_framer.h
+++ b/extensions/browser/api/cast_channel/cast_framer.h
@@ -12,7 +12,7 @@
 #include "net/base/io_buffer.h"
 
 namespace extensions {
-namespace core_api {
+namespace api {
 namespace cast_channel {
 class CastMessage;
 
@@ -94,6 +94,6 @@ class MessageFramer {
   DISALLOW_COPY_AND_ASSIGN(MessageFramer);
 };
 }  // namespace cast_channel
-}  // namespace core_api
+}  // namespace api
 }  // namespace extensions
 #endif  // EXTENSIONS_BROWSER_API_CAST_CHANNEL_CAST_FRAMER_H_