[cc] Migrate ImageController tests to TaskEnvironment.

TaskEnvironment is the recommended primitive to use for tests that
post tasks.

Change-Id: I6a8a434869acc803d7c3d983d1e4d943f0670710
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3698124
Reviewed-by: Vladimir Levin <vmpstr@chromium.org>
Commit-Queue: Francois Pierre Doray <fdoray@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1013561}

cc/tiles/image_controller_unittest.cc

@@ -11,11 +11,12 @@
 #include "base/callback_helpers.h"
 #include "base/run_loop.h"
 #include "base/synchronization/condition_variable.h"
-#include "base/test/test_simple_task_runner.h"
+#include "base/task/thread_pool.h"
 #include "base/threading/sequenced_task_runner_handle.h"
 #include "base/threading/simple_thread.h"
 #include "base/threading/thread_checker_impl.h"
 #include "cc/paint/paint_image_builder.h"
+#include "cc/test/cc_test_suite.h"
 #include "cc/test/skia_common.h"
 #include "cc/test/stub_decode_cache.h"
 #include "cc/test/test_paint_worklet_input.h"
@@ -26,78 +27,6 @@
 namespace cc {
 namespace {
 
-class TestWorkerThread : public base::SimpleThread {
- public:
-  TestWorkerThread()
-      : base::SimpleThread("test_worker_thread"), condition_(&lock_) {}
-
-  void Run() override {
-    for (;;) {
-      base::OnceClosure task;
-      {
-        base::AutoLock hold(lock_);
-        if (shutdown_)
-          break;
-
-        if (queue_.empty()) {
-          condition_.Wait();
-          continue;
-        }
-
-        task = std::move(queue_.front());
-        queue_.erase(queue_.begin());
-      }
-      std::move(task).Run();
-    }
-  }
-
-  void Shutdown() {
-    base::AutoLock hold(lock_);
-    shutdown_ = true;
-    condition_.Signal();
-  }
-
-  void PostTask(base::OnceClosure task) {
-    base::AutoLock hold(lock_);
-    queue_.push_back(std::move(task));
-    condition_.Signal();
-  }
-
- private:
-  base::Lock lock_;
-  base::ConditionVariable condition_;
-  std::vector<base::OnceClosure> queue_;
-  bool shutdown_ = false;
-};
-
-class WorkerTaskRunner : public base::SequencedTaskRunner {
- public:
-  WorkerTaskRunner() { thread_.Start(); }
-
-  bool PostNonNestableDelayedTask(const base::Location& from_here,
-                                  base::OnceClosure task,
-                                  base::TimeDelta delay) override {
-    return PostDelayedTask(from_here, std::move(task), delay);
-  }
-
-  bool PostDelayedTask(const base::Location& from_here,
-                       base::OnceClosure task,
-                       base::TimeDelta delay) override {
-    thread_.PostTask(std::move(task));
-    return true;
-  }
-
-  bool RunsTasksInCurrentSequence() const override { return false; }
-
- protected:
-  ~WorkerTaskRunner() override {
-    thread_.Shutdown();
-    thread_.Join();
-  }
-
-  TestWorkerThread thread_;
-};
-
 // Image decode cache with introspection!
 class TestableCache : public StubDecodeCache {
  public:
@@ -263,16 +192,16 @@ class ImageControllerTest : public testing::Test {
   ~ImageControllerTest() override = default;
 
   void SetUp() override {
-    worker_task_runner_ = base::MakeRefCounted<WorkerTaskRunner>();
-    controller_ = std::make_unique<ImageController>(task_runner_.get(),
-                                                    worker_task_runner_);
+    controller_ = std::make_unique<ImageController>(
+        task_runner_,
+        base::ThreadPool::CreateSequencedTaskRunner(base::TaskTraits()));
     cache_ = TestableCache();
     controller_->SetImageDecodeCache(&cache_);
   }
 
   void TearDown() override {
     controller_.reset();
-    worker_task_runner_ = nullptr;
+    CCTestSuite::RunUntilIdle();
     weak_ptr_factory_.InvalidateWeakPtrs();
   }
 
@@ -319,7 +248,6 @@ class ImageControllerTest : public testing::Test {
 
  private:
   scoped_refptr<base::SequencedTaskRunner> task_runner_;
-  scoped_refptr<WorkerTaskRunner> worker_task_runner_;
   TestableCache cache_;
   std::unique_ptr<ImageController> controller_;
   DrawImage image_;