Don't allow multiple opens for Pepper FileSystem.

BUG=73667
TEST=test_file_system.{h,cc}

Review URL: http://codereview.chromium.org/6596026

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@76278 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/ppapi/ppapi_tests.gypi b/ppapi/ppapi_tests.gypi
index a8f4bae..a3de9bb4 100644
--- a/ppapi/ppapi_tests.gypi
+++ b/ppapi/ppapi_tests.gypi
@@ -190,6 +190,8 @@
         'tests/test_file_io.h',
         'tests/test_file_ref.cc',
         'tests/test_file_ref.h',
+        'tests/test_file_system.cc',
+        'tests/test_file_system.h',
         'tests/test_graphics_2d.cc',
         'tests/test_graphics_2d.h',
         'tests/test_image_data.cc',