Use the new trim modes in the GN build.

build/toolchain/win/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/win/visual_studio_version.gni")
 import("//build/toolchain/goma.gni")
 
 # Should only be running on Windows.
 assert(is_win)
 
 # Setup the Visual Studio state.
 #
 # Its arguments are the VS path and the compiler wrapper tool. It will write
 # "environment.x86" and "environment.x64" to the build directory and return a
 # list to us.
 gyp_win_tool_path = rebase_path("//tools/gyp/pylib/gyp/win_tool.py",
                                 root_build_dir)
 exec_script("setup_toolchain.py",
-            [ visual_studio_path, gyp_win_tool_path, windows_sdk_path ],
-            "string")
+            [ visual_studio_path, gyp_win_tool_path, windows_sdk_path ])
 
 stamp_command = "$python_path gyp-win-tool stamp \$out"
 copy_command = "$python_path gyp-win-tool recursive-mirror \$in \$out"
 
 # MSVC can't share PDB files between compilers compiling C and C++ files, so
 # we construct different names for each type.
 c_pdb_suffix = " /Fd\${target_out_dir}/\${target_name}_c.pdb"
 cc_pdb_suffix = " /Fd\${target_out_dir}/\${target_name}_cc.pdb"
 
 # 32-bit toolchain -------------------------------------------------------------
@@ skipping 115 matching lines @@
 
   # When invoking this toolchain not as the default one, these args will be
   # passed to the build. They are ignored when this is the default toolchain.
   toolchain_args() {
     cpu_arch = "x64"
     # Normally the build config resets the CPU architecture to 32-bits. Setting
     # this flag overrides that behavior.
     force_win64 = true
   }
 }