Allow unit tests to force serial execution in the test launcher.

ui/base/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("//testing/test.gni")
 
 if (is_android) {
   import("//build/config/android/config.gni")
   import("//build/config/android/rules.gni")
@@ skipping 396 matching lines @@
     ]
   }
 
   libs = []
   if (is_win) {
     sources += [
       "cursor/cursor_loader_win.cc",
       "cursor/cursor_loader_win.h",
     ]
     deps += [ "//third_party/wtl" ]
-    cflags = [
-      "/wd4324",  # Structure was padded due to __declspec(align()), which is
-                  # uninteresting.
-    ]
+    cflags = [ "/wd4324" ]  # Structure was padded due to __declspec(align()), which is
+                            # uninteresting.
+
     ldflags = [
       "/DELAYLOAD:d2d1.dll",
       "/DELAYLOAD:d3d10_1.dll",
       "/DELAYLOAD:dwmapi.dll",
     ]
     libs += [
       "d2d1.lib",
       "d3d10_1.lib",
       "dwmapi.lib",
       "d2d1.lib",
@@ skipping 214 matching lines @@
 
   if (is_ios) {
     # Compile this Mac file on iOS as well.
     set_sources_assignment_filter([])
     sources += [ "l10n/l10n_util_mac_unittest.mm" ]
     set_sources_assignment_filter(sources_assignment_filter)
   } else {  # !is_ios
     sources += [
       "accelerators/accelerator_manager_unittest.cc",
       "accelerators/menu_label_accelerator_util_linux_unittest.cc",
+      "clipboard/clipboard_unittest.cc",
       "clipboard/custom_data_helper_unittest.cc",
       "cocoa/base_view_unittest.mm",
       "cocoa/cocoa_base_utils_unittest.mm",
       "cocoa/controls/blue_label_button_unittest.mm",
       "cocoa/controls/hover_image_menu_button_unittest.mm",
       "cocoa/controls/hyperlink_button_cell_unittest.mm",
       "cocoa/controls/hyperlink_text_view_unittest.mm",
       "cocoa/focus_tracker_unittest.mm",
       "cocoa/fullscreen_window_manager_unittest.mm",
       "cocoa/hover_image_button_unittest.mm",
@@ skipping 136 matching lines @@
   }
 
   if (is_chromeos) {
     deps += [
       "//chromeos",
       "//ui/events:dom4_keycode_converter",
     ]
   }
 }
 # TODO(GYP) Mac (ui_base_tests_bundle)