Rework how isolates are generated in MB.

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 598 matching lines @@
       "../android/java/src/org/chromium/ui/base/DeviceFormFactor.java",
       "../android/java/src/org/chromium/ui/base/LocalizationUtils.java",
       "../android/java/src/org/chromium/ui/base/ResourceBundle.java",
       "../android/java/src/org/chromium/ui/base/SelectFileDialog.java",
       "../android/java/src/org/chromium/ui/base/TouchDevice.java",
     ]
     jni_package = "base"
   }
 }
 
+#
+# TODO(GYP): Delete this after we've converted everything to GN.
+# The _run targets exist only for compatibility w/ GYP.
+group("ui_base_unittests_run") {
+  testonly = true
+  deps = [
+    ":ui_base_unittests",
+  ]
+}
+
 # GYP version: ui/base/ui_base_tests.gyp:ui_base_unittests
 test("ui_base_unittests") {
   sources = [
     "ios/cru_context_menu_controller_unittest.mm",
     "l10n/l10n_util_mac_unittest.mm",
     "l10n/l10n_util_unittest.cc",
     "l10n/l10n_util_win_unittest.cc",
     "l10n/time_format_unittest.cc",
     "layout_unittest.cc",
     "models/tree_node_iterator_unittest.cc",
@@ skipping 173 matching lines @@
   }
 
   if (is_chromeos) {
     deps += [
       "//chromeos",
       "//ui/events:dom_keycode_converter",
     ]
   }
 }
 # TODO(GYP) Mac (ui_base_tests_bundle)