[Mac/GN] Add a new linker_driver.py option to save unstripped linker output.

build/config/mac/BUILD.gn

 # Copyright (c) 2013 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/sysroot.gni")
 import("//build/config/mac/mac_sdk.gni")
 import("//build/config/mac/symbols.gni")
 
 # This is included by reference in the //build/config/compiler config that
 # is applied to all targets. It is here to separate out the logic.
@@ skipping 30 matching lines @@
   cflags = common_mac_flags
 
   # Without this, the constructors and destructors of a C++ object inside
   # an Objective C struct won't be called, which is very bad.
   cflags_objcc = [ "-fobjc-call-cxx-cdtors" ]
 
   cflags_c = [ "-std=c99" ]
   cflags_objc = cflags_c
 
   ldflags = common_mac_flags
+
+  if (save_unstripped_output) {
+    ldflags += [ "-Wcrl,unstripped," + rebase_path(root_out_dir) ]
+  }
 }
 
 # This is included by reference in the //build/config/compiler:runtime_library
 # config that is applied to all targets. It is here to separate out the logic
 # that is Mac-only. Please see that target for advice on what should go in
 # :runtime_library vs. :compiler.
 config("runtime_library") {
   common_flags = [
     "-isysroot",
     sysroot,
@@ skipping 39 matching lines @@
 # //build/toolchain/mac/linker_driver.py.
 # Remove this config if a target wishes to change the arguments passed to the
 # strip command during linking. This config by default strips all symbols
 # from a binary, but some targets may wish to specify a saves file to preserve
 # specific symbols.
 config("strip_all") {
   if (enable_stripping) {
     ldflags = [ "-Wcrl,strip,-x,-S" ]
   }
 }