Use ScopedTaskEnvironment instead of MessageLoop in third_party unit tests.

third_party/zlib/google/zip_reader_unittest.cc

Index: third_party/zlib/google/zip_reader_unittest.cc
diff --git a/third_party/zlib/google/zip_reader_unittest.cc b/third_party/zlib/google/zip_reader_unittest.cc
index 4e023dc28328c1643083f9c18f61708ef08fbc30..3056aba8ab855d03c91d35c71e7da24db721bdaa 100644
--- a/third_party/zlib/google/zip_reader_unittest.cc
+++ b/third_party/zlib/google/zip_reader_unittest.cc
@@ -22,6 +22,7 @@
 #include "base/run_loop.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
+#include "base/test/scoped_task_environment.h"
 #include "base/time/time.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -188,7 +189,7 @@ class ZipReaderTest : public PlatformTest {
 
   base::ScopedTempDir temp_dir_;
 
-  base::MessageLoop message_loop_;
+  base::test::ScopedTaskEnvironment scoped_task_environment_;
 };
 
 TEST_F(ZipReaderTest, Open_ValidZipFile) {