Add missing IWYU message_loop.h includes.

ui/gfx/text_elider_unittest.cc

 // Copyright (c) 2012 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.
 //
 // Unit tests for eliding and formatting utility functions.
 
 #include "ui/gfx/text_elider.h"
 
 #include <stddef.h>
 
 #include <memory>
 #include <vector>
 
 #include "base/files/file_path.h"
 #include "base/i18n/rtl.h"
 #include "base/macros.h"
+#include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "build/build_config.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/gfx/font.h"
 #include "ui/gfx/font_list.h"
 #include "ui/gfx/font_render_params.h"
 #include "ui/gfx/text_utils.h"
 
@@ skipping 1115 matching lines @@
 
   // Test breaking in the middle of the first word, with leading whitespace.
   EXPECT_EQ(L"\x2026", UTF16ToWide(TruncateString(str2, 4, WORD_BREAK)));
   EXPECT_EQ(L"\x2026", UTF16ToWide(TruncateString(str2, 4, CHARACTER_BREAK)));
   EXPECT_EQ(L"   f\x2026", UTF16ToWide(TruncateString(str2, 5, WORD_BREAK)));
   EXPECT_EQ(L"   f\x2026",
             UTF16ToWide(TruncateString(str2, 5, CHARACTER_BREAK)));
 }
 
 }  // namespace gfx