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

tools/gn/toolchain.h

 // Copyright (c) 2013 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.
 
 #ifndef TOOLS_GN_TOOLCHAIN_H_
 #define TOOLS_GN_TOOLCHAIN_H_
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/string_piece.h"
@@ skipping 26 matching lines @@
     TYPE_OBJC,
     TYPE_OBJCXX,
     TYPE_RC,
     TYPE_ASM,
     TYPE_ALINK,
     TYPE_SOLINK,
     TYPE_SOLINK_MODULE,
     TYPE_LINK,
     TYPE_STAMP,
     TYPE_COPY,
+    TYPE_COPY_BUNDLE_DATA,
+    TYPE_COMPILE_XCASSETS,
 
     TYPE_NUMTYPES  // Must be last.
   };
 
   static const char* kToolCc;
   static const char* kToolCxx;
   static const char* kToolObjC;
   static const char* kToolObjCxx;
   static const char* kToolRc;
   static const char* kToolAsm;
   static const char* kToolAlink;
   static const char* kToolSolink;
   static const char* kToolSolinkModule;
   static const char* kToolLink;
   static const char* kToolStamp;
   static const char* kToolCopy;
+  static const char* kToolCopyBundleData;
+  static const char* kToolCompileXCAssets;
 
   Toolchain(const Settings* settings, const Label& label);
   ~Toolchain() override;
 
   // Item overrides.
   Toolchain* AsToolchain() override;
   const Toolchain* AsToolchain() const override;
 
   // Returns TYPE_NONE on failure.
   static ToolType ToolNameToType(const base::StringPiece& str);
@@ skipping 49 matching lines @@
   bool setup_complete_;
 
   // Substitutions used by the tools in this toolchain.
   SubstitutionBits substitution_bits_;
 
   LabelTargetVector deps_;
   Scope::KeyValueMap args_;
 };
 
 #endif  // TOOLS_GN_TOOLCHAIN_H_