Do not flush SequencedWorkerPools in browser tests.

ios/web/test/web_test_suite.mm

Index: ios/web/test/web_test_suite.mm
diff --git a/ios/web/test/web_test_suite.mm b/ios/web/test/web_test_suite.mm
index b0edc6f21dd3a43313d1e367f4958f02d352f333..11102ec8df44557e78aeecfd06b897fe93608898 100644
--- a/ios/web/test/web_test_suite.mm
+++ b/ios/web/test/web_test_suite.mm
@@ -4,29 +4,16 @@
 
 #include "ios/web/public/test/web_test_suite.h"
 
-#include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/metrics/statistics_recorder.h"
 #include "base/path_service.h"
 #import "ios/web/public/test/test_web_client.h"
 #include "ios/web/public/url_schemes.h"
-#include "ios/web/web_thread_impl.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/base/resource/resource_bundle.h"
 
 namespace web {
 
-class WebTestSuiteListener : public testing::EmptyTestEventListener {
- public:
-  WebTestSuiteListener() {}
-  void OnTestEnd(const testing::TestInfo& test_info) override {
-    WebThreadImpl::FlushThreadPoolHelperForTesting();
-  }
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(WebTestSuiteListener);
-};
-
 WebTestSuite::WebTestSuite(int argc, char** argv)
     : base::TestSuite(argc, argv),
       web_client_(base::WrapUnique(new TestWebClient)) {}
@@ -41,9 +28,6 @@ void WebTestSuite::Initialize() {
   // by tests.
   base::StatisticsRecorder::Initialize();
 
-  testing::UnitTest::GetInstance()->listeners().Append(
-      new WebTestSuiteListener);
-
   RegisterWebSchemes(false);
 
   // Force unittests to run using en-US so if testing string output will work