Unbundle opus

This CL makes it easier for Linux distribution packagers to use system
opus codec library, by providing a drop-in replacement GN file.

build/linux/unbundle is a separate directory tree, so that regular
Chromium developers don't need to worry about this configuration.

Please see https://cs.chromium.org/chromium/src/build/linux/unbundle/README?dr
for more context.

BUG=551343
R=thestig@chromium.org

Review-Url: https://codereview.chromium.org/2838423002 .
Cr-Original-Commit-Position: refs/heads/master@{#467451}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 5e44d52a673058600ca83f0163cded8405c5a8bd

linux/unbundle/opus.gn

@@ -0,0 +1,45 @@
+# Copyright 2017 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/shim_headers.gni")
+
+pkg_config("system_opus") {
+  packages = [ "opus" ]
+}
+
+shim_headers("opus_shim") {
+  root_path = "src/include"
+  headers = [
+    "opus.h",
+    "opus_defines.h",
+    "opus_multistream.h",
+    "opus_types.h",
+  ]
+}
+
+source_set("opus") {
+  deps = [
+    ":opus_shim",
+  ]
+  public_configs = [ ":system_opus" ]
+}
+
+source_set("opus_compare") {
+}
+
+source_set("opus_demo") {
+}
+
+source_set("test_opus_api") {
+}
+
+source_set("test_opus_decode") {
+}
+
+source_set("test_opus_encode") {
+}
+
+source_set("test_opus_padding") {
+}

linux/unbundle/replace_gn_files.py

@@ -29,6 +29,7 @@ REPLACEMENTS = {
   'libwebp': 'third_party/libwebp/BUILD.gn',
   'libxml': 'third_party/libxml/BUILD.gn',
   'libxslt': 'third_party/libxslt/BUILD.gn',
+  'opus': 'third_party/opus/BUILD.gn',
   're2': 'third_party/re2/BUILD.gn',
   'snappy': 'third_party/snappy/BUILD.gn',
   'yasm': 'third_party/yasm/yasm_assemble.gni',