Land prep work to enable NaCl in the Linux x64 GN builds.

base/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/ui.gni")
 import("//testing/test.gni")
 
 if (is_android) {
   import("//build/config/android/rules.gni")
 }
@@ skipping 746 matching lines @@
     "win/startup_information.h",
     "win/win_util.cc",
     "win/win_util.h",
     "win/windows_version.cc",
     "win/windows_version.h",
     "win/wrapped_window_proc.cc",
     "win/wrapped_window_proc.h",
   ]
 
   if (is_nacl) {
-    sources += [ "files/file_path_watcher_stub.cc" ]
+    # We reset sources_assignment_filter in order to explicitly include
+    # the linux file (which would otherwise be filtered out).
+    set_sources_assignment_filter([])
+    sources += [
+      "files/file_path_watcher_stub.cc",
+      "sync_socket_nacl.cc",
+      "threading/platform_thread_linux.cc",
+    ]
+    set_sources_assignment_filter(sources_assignment_filter)
+
+    sources -= [
+      "allocator/type_profiler_control.cc",
+      "allocator/type_profiler_control.h",
+      "async_socket_io_handler_posix.cc",
+      "base_paths.cc",
+      "cpu.cc",
+      "files/file_proxy.cc",
+      "files/file_util.cc",
+      "files/file_util_proxy.cc",
+      "path_service.cc",
+      "scoped_native_library.cc",
+      "files/scoped_temp_dir.cc",
+    ]
   }
 
   sources -= [
     "process/process_handle_freebsd.cc",
     "process/process_handle_openbsd.cc",
     "process/process_iterator_freebsd.cc",
     "process/process_iterator_openbsd.cc",
     "process/process_metrics_freebsd.cc",
     "process/process_metrics_openbsd.cc",
     "sys_info_freebsd.cc",
@@ skipping 67 matching lines @@
       "files/file_enumerator_posix.cc",
       "files/file_util_posix.cc",
       "memory/shared_memory_posix.cc",
       "message_loop/message_pump_libevent.cc",
       "metrics/field_trial.cc",
       "native_library_posix.cc",
       "process/kill_posix.cc",
       "process/launch_posix.cc",
       "process/process_metrics_posix.cc",
       "process/process_posix.cc",
+      "rand_util_posix.cc",
       "sync_socket_posix.cc",
       "sys_info_posix.cc",
     ]
   } else {
-    # Remove nacl stuff.
+    # Remove NaCl stuff.
     sources -= [
       "memory/shared_memory_nacl.cc",
       "os_compat_nacl.cc",
       "os_compat_nacl.h",
       "rand_util_nacl.cc",
     ]
   }
 
   # Windows.
   if (is_win) {
@@ skipping 698 matching lines @@
 
   # GYP: //base.gyp:base_java_unittest_support
   android_library("base_java_unittest_support") {
     deps = [
       ":base_java",
     ]
     java_files =
         [ "test/android/java/src/org/chromium/base/ContentUriTestUtils.java" ]
   }
 }