GN: Fix some breakage for os==chromeos build

build/config/linux/BUILD.gn

 # 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.
 
 import("//build/config/linux/pkg_config.gni")
 import("//build/config/features.gni")
 import("//build/config/sysroot.gni")
 import("//build/config/ui.gni")
 import("//tools/generate_library_loader/generate_library_loader.gni")
 
@@ skipping 124 matching lines @@
     defines = [ "USE_BRLAPI" ]
   }
 
   # TODO(GYP) linux_link_brlapi support. Is this needed?
   generate_library_loader("libbrlapi") {
     name = "LibBrlapiLoader"
     output_h = "libbrlapi.h"
     output_cc = "libbrlapi_loader.cc"
     header = "<brlapi.h>"
     config = ":brlapi_config"
+
+    functions = [
+      "brlapi_getHandleSize",
+      "brlapi_error_location",
+      "brlapi_strerror",
+      "brlapi__acceptKeys",
+      "brlapi__openConnection",
+      "brlapi__closeConnection",
+      "brlapi__getDisplaySize",
+      "brlapi__enterTtyModeWithPath",
+      "brlapi__leaveTtyMode",
+      "brlapi__writeDots",
+      "brlapi__readKey",
+    ]
   }
 }
 
 pkg_config("gio_config") {
   packages = [ "gio-2.0" ]
   # glib >=2.40 deprecate g_settings_list_schemas in favor of
   # g_settings_schema_source_list_schemas. This function is not available on
   # earlier versions that we still need to support (specifically, 2.32), so
   # disable the warning with the GLIB_DISABLE_DEPRECATION_WARNINGS define.
   # TODO(mgiuca): Remove this suppression when we drop support for Ubuntu 13.10
@@ skipping 33 matching lines @@
     "pci_alloc",
     "pci_init",
     "pci_cleanup",
     "pci_scan_bus",
     "pci_fill_info",
     "pci_lookup_name",
   ]
 }
 
 # Looking for libspeechd? Use //third_party/speech-dispatcher