[MBI] Add default_task_queue to AgentGroupSchedulerImpl

[related design doc]
https://docs.google.com/document/d/1y-vHkrD1z2RtyWYwT6rJkSLHClYNjDDpUbTtBU7l95A

Bug: 1105403
Change-Id: I28ca5b34a0285d679e98786c84ed9c1b08a230a9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2413929
Commit-Queue: Minoru Chikamune <chikamune@chromium.org>
Reviewed-by: Tal Pressman <talp@chromium.org>
Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#808185}

third_party/blink/renderer/platform/scheduler/main_thread/agent_group_scheduler_impl.cc

@@ -4,11 +4,18 @@
 
 #include "third_party/blink/renderer/platform/scheduler/main_thread/agent_group_scheduler_impl.h"
 
+#include "third_party/blink/public/platform/task_type.h"
 #include "third_party/blink/renderer/platform/scheduler/main_thread/main_thread_scheduler_impl.h"
 
 namespace blink {
 namespace scheduler {
 
+MainThreadTaskQueue::QueueCreationParams DefaultTaskQueueCreationParams() {
+  return MainThreadTaskQueue::QueueCreationParams(
+             MainThreadTaskQueue::QueueType::kDefault)
+      .SetShouldMonitorQuiescence(true);
+}
+
 static AgentGroupSchedulerImpl* g_current_agent_group_scheduler_impl;
 
 // static
@@ -26,9 +33,14 @@ void AgentGroupSchedulerImpl::SetCurrent(
 
 AgentGroupSchedulerImpl::AgentGroupSchedulerImpl(
     MainThreadSchedulerImpl* main_thread_scheduler)
-    : main_thread_scheduler_(main_thread_scheduler) {}
+    : default_task_queue_(main_thread_scheduler->NewTaskQueue(
+          DefaultTaskQueueCreationParams())),
+      default_task_runner_(default_task_queue_->CreateTaskRunner(
+          TaskType::kMainThreadTaskQueueDefault)),
+      main_thread_scheduler_(main_thread_scheduler) {}
 
 AgentGroupSchedulerImpl::~AgentGroupSchedulerImpl() {
+  default_task_queue_->ShutdownTaskQueue();
   if (main_thread_scheduler_) {
     main_thread_scheduler_->RemoveAgentGroupScheduler(this);
   }

third_party/blink/renderer/platform/scheduler/main_thread/agent_group_scheduler_impl.h

@@ -5,14 +5,18 @@
 #ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_SCHEDULER_MAIN_THREAD_AGENT_GROUP_SCHEDULER_IMPL_H_
 #define THIRD_PARTY_BLINK_RENDERER_PLATFORM_SCHEDULER_MAIN_THREAD_AGENT_GROUP_SCHEDULER_IMPL_H_
 
+#include "base/memory/scoped_refptr.h"
 #include "third_party/blink/renderer/platform/platform_export.h"
 #include "third_party/blink/renderer/platform/scheduler/public/agent_group_scheduler.h"
 
-#include <memory>
+namespace base {
+class SingleThreadTaskRunner;
+}
 
 namespace blink {
 namespace scheduler {
 class MainThreadSchedulerImpl;
+class MainThreadTaskQueue;
 
 // AgentGroupScheduler implementation which schedules per-AgentSchedulingGroup
 // tasks.
@@ -26,11 +30,16 @@ class PLATFORM_EXPORT AgentGroupSchedulerImpl
   AgentGroupSchedulerImpl(const AgentGroupSchedulerImpl&) = delete;
   AgentGroupSchedulerImpl& operator=(const AgentGroupSchedulerImpl&) = delete;
   ~AgentGroupSchedulerImpl() override;
+  scoped_refptr<base::SingleThreadTaskRunner> DefaultTaskRunner() {
+    return default_task_runner_;
+  }
   MainThreadSchedulerImpl* GetMainThreadScheduler() {
     return main_thread_scheduler_;
   }
 
  private:
+  scoped_refptr<MainThreadTaskQueue> default_task_queue_;
+  scoped_refptr<base::SingleThreadTaskRunner> default_task_runner_;
   MainThreadSchedulerImpl* main_thread_scheduler_;  // Not owned.
 };