Provide dummy Android UI thread with looper for C++ unit tests

base/test/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")
 
 if (is_android) {
   import("//build/config/android/rules.gni")
 }
 
@@ skipping 94 matching lines @@
     "test_shortcut_win.cc",
     "test_shortcut_win.h",
     "test_simple_task_runner.cc",
     "test_simple_task_runner.h",
     "test_suite.cc",
     "test_suite.h",
     "test_support_android.cc",
     "test_support_android.h",
     "test_support_ios.h",
     "test_support_ios.mm",
+    "test_ui_thread_android.cc",
+    "test_ui_thread_android.h",
     "thread_test_helper.cc",
     "thread_test_helper.h",
     "trace_event_analyzer.cc",
     "trace_event_analyzer.h",
     "trace_to_file.cc",
     "trace_to_file.h",
     "user_action_tester.cc",
     "user_action_tester.h",
     "values_test_util.cc",
     "values_test_util.h",
@@ skipping 71 matching lines @@
     deps = [
       "//base",
     ]
   }
 }
 
 if (is_android) {
   generate_jni("base_unittests_jni_headers") {
     sources = [
       "android/java/src/org/chromium/base/ContentUriTestUtils.java",
+      "android/java/src/org/chromium/base/TestUiThread.java",
     ]
     jni_package = "base"
   }
 }