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

extensions/browser/api/document_scan/document_scan_interface_nonchromeos.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/document_scan_interface.h"
 
 namespace {
 
 const char kScanFunctionNotImplementedError[] = "Scan function not implemented";
 
 }  // namespace
 
 namespace extensions {
 
-namespace core_api {
+namespace api {
 
 class DocumentScanInterfaceImpl : public DocumentScanInterface {
  public:
   DocumentScanInterfaceImpl() {}
   ~DocumentScanInterfaceImpl() override {}
 
   void ListScanners(const ListScannersResultsCallback& callback) override {
     callback.Run(std::vector<ScannerDescription>(), "");
   }
   void Scan(const std::string& scanner_name,
             ScanMode mode,
             int resolution_dpi,
             const ScanResultsCallback& callback) override {
     callback.Run("", "", kScanFunctionNotImplementedError);
   }
 
  private:
   DISALLOW_COPY_AND_ASSIGN(DocumentScanInterfaceImpl);
 };
 
 // static
 DocumentScanInterface* DocumentScanInterface::CreateInstance() {
   return new DocumentScanInterfaceImpl();
 }
 
-}  // namespace core_api
+}  // namespace api
 
 }  // namespace extensions