Fix include directories in Windows GN build.

build/json_schema_api.gni

 # 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.
 
 # Defines a static library corresponding to the output of schema compiler tools
 # over a set of extensions API schemas (IDL or JSON format.) The library target
 # has implicit hard dependencies on all schema files listed by the invoker and
 # is itself a hard dependency.
 #
 # Invocations of this template may use the following variables:
@@ skipping 53 matching lines @@
   if (defined(invoker.schema_include_rules)) {
     schema_include_rules = invoker.schema_include_rules
   }
 
   # Keep a copy of the target_name here since it will be trampled
   # in nested targets.
   target_visibility = [ ":$target_name" ]
 
   generated_config_name = target_name + "_generated_config"
   config(generated_config_name) {
-    include_dirs = [ target_gen_dir ]

[Slava Chigrin, 2015/01/13 15:46:05]

Here target_gen_dir is something like //out/gnRel/gen/extensions/common/api
and  root_gen_dir is like
//out/gnRel/gen

We must NOT add target_gen_dir  to the include path, since there is file
windows.h in directory //out/gnRel/gen/extensions/common/api . That causes
conflicts with system header with the same name, producing a lot of weird
compile errors on Windows.

Generated file included in chrome by more specific path, like
#include "chrome/common/extensions/api/windows.h" , so everyting should be OK
after that fix.

+    include_dirs = [ root_gen_dir ]
     visibility = target_visibility
   }
 
   sources = invoker.sources
   root_namespace = invoker.root_namespace
 
   compiler_root = "//tools/json_schema_compiler"
   compiler_script = "$compiler_root/compiler.py"
   compiler_sources = [
     "$compiler_root/cc_generator.py",
@@ skipping 119 matching lines @@
     public_configs = [ ":$generated_config_name" ]
 
     if (defined(invoker.visibility)) {
       visibility = invoker.visibility
     }
     if (defined(invoker.output_name)) {
       output_name = invoker.output_name
     }
   }
 }