Update from chromium https://crrev.com/301315

gpu/command_buffer/service/BUILD.gn

 # Copyright 2014 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/ui.gni")
 import("//third_party/protobuf/proto_library.gni")
 
 source_set("service") {
   sources = [
     "async_pixel_transfer_delegate.cc",
@@ skipping 57 matching lines @@
     "gpu_tracer.cc",
     "gpu_tracer.h",
     "id_manager.h",
     "id_manager.cc",
     "image_manager.cc",
     "image_manager.h",
     "in_process_command_buffer.cc",
     "in_process_command_buffer.h",
     "logger.cc",
     "logger.h",
-    "mailbox_manager.cc",
     "mailbox_manager.h",
-    "mailbox_synchronizer.cc",
-    "mailbox_synchronizer.h",
+    "mailbox_manager_impl.cc",
+    "mailbox_manager_impl.h",
+    "mailbox_manager_sync.cc",
+    "mailbox_manager_sync.h",
     "memory_program_cache.h",
     "memory_program_cache.cc",
     "mocks.h",
     "program_manager.h",
     "program_manager.cc",
     "query_manager.h",
     "query_manager.cc",
     "renderbuffer_manager.h",
     "renderbuffer_manager.cc",
     "program_cache.h",
@@ skipping 58 matching lines @@
   if (is_android && !is_debug) {
     # On Android optimize more since this component can be a bottleneck.
     configs -= [ "//build/config/compiler:optimize" ]
     configs += [ "//build/config/compiler:optimize_max" ]
   }
 }
 
 proto_library("disk_cache_proto") {
   sources = [ "disk_cache_proto.proto" ]
 }