Add CefTaskManager API

See https://tests/task_manager example in cefclient.

libcef/browser/task_manager_impl.h

@@ -0,0 +1,47 @@
+// Copyright (c) 2024 The Chromium Embedded Framework Authors. All rights
+// reserved. Use of this source code is governed by a BSD-style license that
+// can be found in the LICENSE file.
+
+#ifndef CEF_LIBCEF_BROWSER_TASK_MANAGER_IMPL_H_
+#define CEF_LIBCEF_BROWSER_TASK_MANAGER_IMPL_H_
+#pragma once
+
+#include "base/memory/raw_ptr.h"
+#include "cef/include/cef_task_manager.h"
+#include "cef/libcef/browser/thread_util.h"
+#include "chrome/browser/task_manager/task_manager_observer.h"
+
+namespace task_manager {
+class TaskManagerInterface;
+}
+
+class CefTaskManagerImpl : public task_manager::TaskManagerObserver,
+                           public CefTaskManager {
+ public:
+  explicit CefTaskManagerImpl(task_manager::TaskManagerInterface* task_manager);
+  ~CefTaskManagerImpl();
+
+  CefTaskManagerImpl(const CefTaskManagerImpl&) = delete;
+  CefTaskManagerImpl& operator=(const CefTaskManagerImpl&) = delete;
+
+  // CefTaskManager methods:
+  size_t GetTasksCount() override;
+  bool GetTaskIdsList(TaskIdList& task_ids) override;
+  bool GetTaskInfo(int64_t task_id, CefTaskInfo& info) override;
+  bool KillTask(int64_t task_id) override;
+
+ private:
+  bool IsValidTaskId(int64_t task_id) const;
+
+  // task_manager::TaskManagerObserver:
+  void OnTaskAdded(int64_t id) override;
+  void OnTaskToBeRemoved(int64_t id) override;
+  void OnTasksRefreshed(const task_manager::TaskIdList& task_ids) override;
+
+  raw_ptr<task_manager::TaskManagerInterface> task_manager_;
+  TaskIdList tasks_;
+
+  IMPLEMENT_REFCOUNTING_DELETE_ON_UIT(CefTaskManagerImpl);
+};
+
+#endif  // CEF_LIBCEF_BROWSER_TASK_MANAGER_IMPL_H_