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

extensions/browser/api/document_scan/mock_document_scan_interface.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "extensions/browser/api/document_scan/mock_document_scan_interface.h"
 
 namespace extensions {
 
-namespace core_api {
+namespace api {
 
 MockDocumentScanInterface::MockDocumentScanInterface() {
 }
 
 MockDocumentScanInterface::~MockDocumentScanInterface() {
 }
 
-}  // namespace core_api
+}  // namespace api
 
 }  // namespace extensions