[iOS] Always generate the final binaries using lipo.

build/toolchain/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.
 
 # TODO(brettw) Use "gcc_toolchain.gni" like the Linux toolchains. This requires
 # some enhancements since the commands on Mac are slightly different than on
 # Linux.
 
 import("../goma.gni")
 import("//build/config/clang/clang.gni")
@@ skipping 73 matching lines @@
     }
 
     cc = "${_compiler_prefix}clang"
     cxx = "${_compiler_prefix}clang++"
     ld = cxx
 
     linker_driver =
         "TOOL_VERSION=${tool_versions.linker_driver} " +
         rebase_path("//build/toolchain/mac/linker_driver.py", root_build_dir)
 
-    if (invoker.toolchain_os == "ios" && additional_toolchains != []) {
-      # For a fat build, the generation of dSYM needs to be performed after the
-      # generation of the fat binaries using "lipo". So disable the generation
-      # of the dSYM for intermediate architecture specific binaries.
+    # On iOS, the final applications are assembled using lipo (to support fat
+    # builds). The correct flags are passed to the linker_driver.py script
+    # directly during the lipo call.
+    if (invoker.toolchain_os != "ios") {
+      _enable_dsyms = enable_dsyms
+      _save_unstripped_output = save_unstripped_output
+    } else {
       _enable_dsyms = false
       _save_unstripped_output = false
-    } else {
-      _enable_dsyms = enable_dsyms
-      _save_unstripped_output = save_unstripped_output
     }
 
     # Make these apply to all tools below.
     lib_switch = "-l"
     lib_dir_switch = "-L"
 
     # Object files go in this directory. Use label_name instead of
     # target_output_name since labels will generally have no spaces and will be
     # unique in the directory.
     object_subdir = "{{target_out_dir}}/{{label_name}}"
@@ skipping 309 matching lines @@
   mac_toolchain("ios_clang_x86") {
     toolchain_cpu = "x86"
     toolchain_os = "ios"
   }
 
   mac_toolchain("ios_clang_x64") {
     toolchain_cpu = "x64"
     toolchain_os = "ios"
   }
 }