Fix gn bootstrap

BUG=833179
R=dpranke

Change-Id: Ie9fa320c6d532844f85d34f5d6f8a1195a9eb107
Reviewed-on: https://chromium-review.googlesource.com/1014263
Commit-Queue: Dirk Pranke <dpranke@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#551134}

tools/gn/bootstrap/bootstrap.py

@@ -530,6 +530,7 @@ def write_gn_ninja(path, root_gen_dir, options, windows_x64_toolchain):
       'base/memory/weak_ptr.cc',
       'base/message_loop/incoming_task_queue.cc',
       'base/message_loop/message_loop.cc',
+      'base/message_loop/message_loop_current.cc',
       'base/message_loop/message_loop_task_runner.cc',
       'base/message_loop/message_pump.cc',
       'base/message_loop/message_pump_default.cc',