Backport some tests in /services/network to SingleThreadTaskEnvironment

These tests were previously migrated from single-threaded MessageLoop to
a multi-threaded TaskEnvironment (then named ScopedTaskEnvironment) as
part of crbug.com/891670.

//base OWNERS decided in retrospect that it was better to keep a
single-threaded option for TaskEnvironment and introduced
SingleThreadTaskEnvironment. This CL retrofits that decision for
/services/network.

This CL is a no-op if it passes CQ.

This CL was uploaded by git cl split.

R=yhirano@chromium.org

Bug: 891670
Change-Id: I4eb4106b83976f08826467577d34c199cce6f468
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1787063
Auto-Submit: Gabriel Charette <gab@chromium.org>
Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Commit-Queue: Yutaka Hirano <yhirano@chromium.org>
Cr-Commit-Position: refs/heads/master@{#693622}

services/network/chunked_data_pipe_upload_data_stream_unittest.cc

@@ -55,8 +55,8 @@ class ChunkedDataPipeUploadDataStreamTest : public testing::Test {
   }
 
  protected:
-  base::test::TaskEnvironment task_environment_{
-      base::test::TaskEnvironment::MainThreadType::IO};
+  base::test::SingleThreadTaskEnvironment task_environment_{
+      base::test::SingleThreadTaskEnvironment::MainThreadType::IO};
   std::unique_ptr<TestChunkedDataPipeGetter> chunked_data_pipe_getter_;
   std::unique_ptr<ChunkedDataPipeUploadDataStream> chunked_upload_stream_;
 

services/network/data_pipe_element_reader_unittest.cc

@@ -91,8 +91,8 @@ class DataPipeElementReaderTest : public testing::Test {
       : element_reader_(nullptr, data_pipe_getter_.GetDataPipeGetterPtr()) {}
 
  protected:
-  base::test::TaskEnvironment task_environment_{
-      base::test::TaskEnvironment::MainThreadType::IO};
+  base::test::SingleThreadTaskEnvironment task_environment_{
+      base::test::SingleThreadTaskEnvironment::MainThreadType::IO};
   PassThroughDataPipeGetter data_pipe_getter_;
   DataPipeElementReader element_reader_;
 };

services/network/restricted_cookie_manager_unittest.cc

@@ -256,8 +256,8 @@ class RestrictedCookieManagerTest
     return recording_client_.recorded_activity();
   }
 
-  base::test::TaskEnvironment task_environment_{
-      base::test::TaskEnvironment::MainThreadType::IO};
+  base::test::SingleThreadTaskEnvironment task_environment_{
+      base::test::SingleThreadTaskEnvironment::MainThreadType::IO};
   net::CookieMonster cookie_monster_;
   CookieSettings cookie_settings_;
   RecordingNetworkContextClient recording_client_;

services/network/throttling/throttling_controller_unittest.cc

@@ -147,8 +147,8 @@ class ThrottlingControllerTestHelper {
   }
 
  private:
-  base::test::TaskEnvironment task_environment_{
-      base::test::TaskEnvironment::TimeSource::MOCK_TIME};
+  base::test::SingleThreadTaskEnvironment task_environment_{
+      base::test::SingleThreadTaskEnvironment::TimeSource::MOCK_TIME};
   MockNetworkLayer network_layer_;
   TestCallback callback_;
   net::CompletionRepeatingCallback completion_callback_;

services/network/websocket_throttler_unittest.cc

@@ -16,7 +16,7 @@ namespace {
 
 class WebSocketThrottlerTest : public ::testing::Test {
  private:
-  base::test::TaskEnvironment task_environment_;
+  base::test::SingleThreadTaskEnvironment task_environment_;
 };
 
 TEST(WebSocketPerProcessThrottlerTest, InitialState) {