Only use sanitizers with default toolchain on Windows as well.

build/toolchain/gcc_toolchain.gni

 # 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/clang/clang.gni")
 import("//build/config/nacl/config.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 import("//build/config/v8_target_cpu.gni")
 import("//build/toolchain/cc_wrapper.gni")
 import("//build/toolchain/goma.gni")
@@ skipping 456 matching lines @@
         use_gold = invoker.use_gold
       }
       if (defined(invoker.use_sysroot)) {
         use_sysroot = invoker.use_sysroot
       }
       if (defined(invoker.v8_toolchain_cpu)) {
         v8_current_cpu = invoker.v8_toolchain_cpu
       } else {
         v8_current_cpu = current_cpu
       }
-
-      # Disable sanitizers for non-default toolchains.
-      is_asan = false
-      is_cfi = false
-      is_lsan = false
-      is_msan = false
-      is_syzyasan = false
-      is_tsan = false
-      is_ubsan = false
-      is_ubsan_null = false
-      is_ubsan_no_recover = false
-      is_ubsan_security = false
-      is_ubsan_vptr = false
-      msan_track_origins = 0
-      sanitizer_coverage_flags = ""
-      use_cfi_diag = false
-      use_custom_libcxx = false
-      use_drfuzz = false
-      use_libfuzzer = false
-      use_prebuilt_instrumented_libraries = false
-      use_locally_built_instrumented_libraries = false
-      use_sanitizer_coverage = false
     }
 
     forward_variables_from(invoker, [ "deps" ])
   }
 }
 
 # This is a shorthand for gcc_toolchain instances based on the
 # Chromium-built version of Clang.  Only the toolchain_cpu and
 # toolchain_os variables need to be specified by the invoker, and
 # optionally toolprefix if it's a cross-compile case.  Note that for
@@ skipping 29 matching lines @@
                              "toolchain_os",
                              "use_gold",
                              "v8_toolchain_cpu",
                            ])
 
     if (defined(invoker.use_debug_fission)) {
       use_debug_fission = invoker.use_debug_fission
     }
   }
 }