Remove a couple of stale BUILD.gn files in build/secondary.

There are now files in the primary locations for flac and trace-viewer.

R=brettw@chromium.org
BUG=

Review URL: https://codereview.chromium.org/690613004

Cr-Commit-Position: refs/heads/master@{#302157}

build/secondary/third_party/flac/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.
-
-config("flac_config") {
-  defines = [ "FLAC__NO_DLL" ]
-}
-
-static_library("flac") {
-  sources = [
-    "include/FLAC/all.h",
-    "include/FLAC/assert.h",
-    "include/FLAC/callback.h",
-    "include/FLAC/export.h",
-    "include/FLAC/format.h",
-    "include/FLAC/metadata.h",
-    "include/FLAC/ordinals.h",
-    "include/FLAC/stream_decoder.h",
-    "include/FLAC/stream_encoder.h",
-    "include/share/alloc.h",
-    "src/libFLAC/alloc.c",
-    "src/libFLAC/bitmath.c",
-    "src/libFLAC/bitreader.c",
-    "src/libFLAC/bitwriter.c",
-    "src/libFLAC/cpu.c",
-    "src/libFLAC/crc.c",
-    "src/libFLAC/fixed.c",
-    "src/libFLAC/float.c",
-    "src/libFLAC/format.c",
-    "src/libFLAC/lpc.c",
-    "src/libFLAC/md5.c",
-    "src/libFLAC/memory.c",
-    "src/libFLAC/stream_decoder.c",
-    "src/libFLAC/stream_encoder.c",
-    "src/libFLAC/stream_encoder_framing.c",
-    "src/libFLAC/window.c",
-    "src/libFLAC/include/private/all.h",
-    "src/libFLAC/include/private/bitmath.h",
-    "src/libFLAC/include/private/bitreader.h",
-    "src/libFLAC/include/private/bitwriter.h",
-    "src/libFLAC/include/private/cpu.h",
-    "src/libFLAC/include/private/crc.h",
-    "src/libFLAC/include/private/fixed.h",
-    "src/libFLAC/include/private/float.h",
-    "src/libFLAC/include/private/format.h",
-    "src/libFLAC/include/private/lpc.h",
-    "src/libFLAC/include/private/md5.h",
-    "src/libFLAC/include/private/memory.h",
-    "src/libFLAC/include/private/metadata.h",
-    "src/libFLAC/include/private/stream_encoder_framing.h",
-    "src/libFLAC/include/private/window.h",
-    "src/libFLAC/include/protected/all.h",
-    "src/libFLAC/include/protected/stream_decoder.h",
-    "src/libFLAC/include/protected/stream_encoder.h",
-  ]
-
-  defines = [
-    "FLAC__OVERFLOW_DETECT",
-    "VERSION=\"1.2.1\"",
-  ]
-
-  configs -= [ "//build/config/compiler:chromium_code" ]
-  configs += [ "//build/config/compiler:no_chromium_code" ]
-  public_configs = [ ":flac_config" ]
-
-  include_dirs = [
-    "include",
-    "src/libFLAC/include",
-  ]
-
-  if (is_clang) {
-    # libflac converts between FLAC__StreamDecoderState and
-    # FLAC__StreamDecoderInitStatus a lot in stream_decoder.c.
-    cflags = [ "-Wno-conversion" ]
-  }
-}