Backport some tests in /services/data_decoder 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/data_decoder.

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

This CL was uploaded by git cl split.

R=rsesek@chromium.org

Bug: 891670
Change-Id: I661e8c04cf53a354ead7ff808eb2636f8a2248ea
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1786970
Auto-Submit: Gabriel Charette <gab@chromium.org>
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Commit-Queue: Robert Sesek <rsesek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#693745}

services/data_decoder/image_decoder_impl_unittest.cc

@@ -108,7 +108,7 @@ class ImageDecoderImplTest : public testing::Test {
   ImageDecoderImpl* decoder() { return &decoder_; }
 
  private:
-  base::test::TaskEnvironment task_environment_;
+  base::test::SingleThreadTaskEnvironment task_environment_;
   ImageDecoderImpl decoder_;
 };
 

services/data_decoder/public/cpp/json_sanitizer_unittest.cc

@@ -46,7 +46,7 @@ class JsonSanitizerTest : public ::testing::Test {
   void OnSuccess(const std::string& json);
   void OnError(const std::string& error);
 
-  base::test::TaskEnvironment task_environment_;
+  base::test::SingleThreadTaskEnvironment task_environment_;
 
 #if !defined(OS_ANDROID)
   TestingJsonParser::ScopedFactoryOverride factory_override_;

services/data_decoder/public/cpp/testing_json_parser_unittest.cc

@@ -56,7 +56,7 @@ class TestingJsonParserTest : public testing::Test {
     EXPECT_FALSE(error.empty());
   }
 
-  base::test::TaskEnvironment task_environment;
+  base::test::SingleThreadTaskEnvironment task_environment;
   TestingJsonParser::ScopedFactoryOverride factory_override_;
   bool did_success_ = false;
   bool did_error_ = false;