Convert GN visibility variables to lists.

ppapi/BUILD.gn

 # 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.
 
 gypi_values = exec_script(
     "//build/gypi_to_gn.py",
     [ rebase_path("ppapi_sources.gypi") ],
     "scope",
     [ "ppapi_sources.gypi" ])
 
 # TODO(GYP) support chrome_multiple_dll
 #if (chrome_multiple_dll) {
 #  blink_target = "//third_party/WebKit/public:blink_minimal"
 #} else {
   blink_target = "//third_party/WebKit/public:blink"
 #}
 
 # These are just headers.
 source_set("ppapi_c") {
   sources = gypi_values.c_source_files
 }
 
+# Some targets need to depend on the PPAPI version only. This target exists so
+# they can include this header without header check warnings.
+source_set("ppapi_macros") {
+  sources = [ "c/pp_macros.h" ]
+}
+
 source_set("ppapi_cpp_objects") {
   sources = gypi_values.cpp_source_files
 
   if (is_win) {
     cflags = [
       "/we4244",  # Implicit conversion, possible loss of data.
     ]
   } else {
     cflags = [
       "-Wextra",
@@ skipping 763 matching lines @@
     ":ppapi_shared",
     "//base/test:test_support",
     "//ipc",
     "//ipc:test_support",
     "//testing/gmock",
     "//testing/gtest",
   ]
 }
 
 # TODO(GYP) other targets from ppapi_tests.gyp