GN: Add -Wl,-z defs on linux and fix errors

media/cdm/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.
 
 import("//build/config/features.gni")
 
 # Android doesn't use ffmpeg.
 use_ffmpeg = !is_android
 
 # The GYP version supports build flags "use_fake_video_decoder" and
 # "use_vpx". These should be added here if necessary but its not clear if
 # they are required any more.
 shared_library("clearkeycdm") {
   sources = [
     "cdm_file_io_test.cc",
     "cdm_file_io_test.h",
     "external_clear_key/cdm_video_decoder.cc",
     "external_clear_key/cdm_video_decoder.h",
     "external_clear_key/clear_key_cdm.cc",
     "external_clear_key/clear_key_cdm.h",
     "external_clear_key/clear_key_cdm_common.h",
   ]
 
   defines = [ "CDM_IMPLEMENTATION" ]
 
   deps = [
     "//base",
+    "//media",  # For media::AudioTimestampHelper
     "//media:shared_memory_support",  # For media::AudioBus.
     "//url",
   ]
 
   if (use_ffmpeg) {
     sources += [
       "external_clear_key/ffmpeg_cdm_audio_decoder.cc",
       "external_clear_key/ffmpeg_cdm_audio_decoder.h",
       "external_clear_key/ffmpeg_cdm_video_decoder.cc",
       "external_clear_key/ffmpeg_cdm_video_decoder.h",
@@ skipping 14 matching lines @@
 
 group("clearkeycdmadapter") {
   deps = [
     #":cdmadapter",  TODO(GYP)
     ":clearkeycdm",
 
     #":clearkeycdmadapter_resources",  TODO(GYP)
     "//ppapi:ppapi_cpp",
   ]
 }