Build addr2line-pdb from tcmalloc for use in memory-infra symbolization

third_party/tcmalloc/BUILD.gn

+# Copyright (c) 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/compiler/compiler.gni")
+
+executable("addr2line-pdb") {

[erikchen, 2017/03/01 22:42:51]

Code search seems to show that most other third_parties use relative paths and
don't require tcmaloc_dir.

https://cs.chromium.org/search/?q=include_dir+file:third_party.*gn&type=cs
https://cs.chromium.org/search/?q=executable+file:third_party.*gn+package:%5E...

Can we try to match their style?

If that doesn't work, it looks like v8 has a slighty less fragile way of getting
the current path:
https://cs.chromium.org/chromium/src/v8/gni/v8.gni?type=cs&q=no_chromium_code...

[awong, 2017/03/01 22:57:00]

Done.

Infact, reduced it even further.

FYI, original code was copied of the tcmalloc target which seems to be following
some outdated conventions perhaps?

+  tcmalloc_dir = "//third_party/tcmalloc/chromium"
+
+  # Don't check tcmalloc's includes. These files include various files like
+  # base/foo.h and they actually refer to tcmalloc's forked copy of base
+  # rather than the regular one, which confuses the header checker.
+  check_includes = false
+
+  sources = [
+    "$tcmalloc_dir/src/windows/addr2line-pdb.c",
+  ]
+
+  include_dirs = [
+    ".",
+    "$tcmalloc_dir/src/base",
+    "$tcmalloc_dir/src",
+  ]
+
+  configs -= [ "//build/config/compiler:chromium_code" ]
+  configs += [ "//build/config/compiler:no_chromium_code" ]
+}