Add testRunner.runIdleTasks() to force idle tasks to run.

components/scheduler/child/idle_helper.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/scheduler/child/idle_helper.h"
 
 #include "base/time/time.h"
 #include "base/trace_event/trace_event.h"
 #include "base/trace_event/trace_event_argument.h"
 #include "components/scheduler/base/real_time_domain.h"
 #include "components/scheduler/base/task_queue.h"
 #include "components/scheduler/base/task_queue_manager.h"
 #include "components/scheduler/child/scheduler_helper.h"
 #include "components/scheduler/child/scheduler_tqm_delegate.h"
 
 namespace scheduler {
 
+namespace {
+
+class IdleTaskObserverForTesting
+    : public base::MessageLoop::TaskObserver {
+ public:
+  IdleTaskObserverForTesting(
+      scoped_refptr<TaskQueue> idle_queue,
+      SchedulerHelper* helper,
+      const base::Closure& finished_callback);
+  void WillProcessTask(const base::PendingTask& pending_task) override;
+  void DidProcessTask(const base::PendingTask& pending_task) override;
+ private:
+  scoped_refptr<TaskQueue> idle_queue_;
+  SchedulerHelper* helper_;
+  base::Closure finished_callback_;
+};
+
+IdleTaskObserverForTesting::IdleTaskObserverForTesting(
+    scoped_refptr<TaskQueue> idle_queue,
+    SchedulerHelper* helper,
+    const base::Closure& finished_callback)
+  : idle_queue_(idle_queue),
+    helper_(helper),
+    finished_callback_(finished_callback) {
+  helper_->AddTaskObserver(this);
+}
+
+void IdleTaskObserverForTesting::WillProcessTask(
+    const base::PendingTask& pending_task) {
+}
+
+void IdleTaskObserverForTesting::DidProcessTask(
+    const base::PendingTask& pending_task)
+{
+  if (idle_queue_->IsEmpty()) {
+    idle_queue_->SetQueueEnabled(false);
+    helper_->DefaultTaskRunner()->PostTask(
+        FROM_HERE, finished_callback_);
+    helper_->RemoveTaskObserver(this);
+    delete this;
+  }
+}
+
+}
+
 IdleHelper::IdleHelper(
     SchedulerHelper* helper,
     Delegate* delegate,
     const char* tracing_category,
     const char* disabled_by_default_tracing_category,
     const char* idle_period_tracing_name,
     base::TimeDelta required_quiescence_duration_before_long_idle_period)
     : helper_(helper),
       delegate_(delegate),
       idle_queue_(
@@ skipping 447 matching lines @@
     case IdlePeriodState::IN_LONG_IDLE_PERIOD_WITH_MAX_DEADLINE:
       return "in_long_idle_period_with_max_deadline";
     case IdlePeriodState::IN_LONG_IDLE_PERIOD_PAUSED:
       return "in_long_idle_period_paused";
     default:
       NOTREACHED();
       return nullptr;
   }
 }
 
+void IdleHelper::RunIdleTasksForTesting(const base::Closure& callback) {
+  new IdleTaskObserverForTesting(idle_queue_, helper_, callback);

[szager1, 2016/03/23 22:55:13]

This is intentional; the instance gets deleted in
IdleTaskObserverForTesting::DidProcessTask.

[Sami, 2016/03/29 11:11:17]

Instead of using an observer, it might be easier just to post an extra idle task
here which invokes the finished callback. (Actually the caller could do that too
which would reduce some of the plumbing here.)

[szager1, 2016/04/06 08:43:17]

Done; I was able to get rid of all changes to IdleHelper.

+  idle_queue_->SetQueueEnabled(true);

[Sami, 2016/03/29 11:11:17]

I think one problem here is that IdleHelper might disable the queue while we're
in the middle of running tasks for tests. Maybe we should add a new flag which
tells the helper that we're flushing idle tasks so it knows to avoid messing
with the queue state?

[szager1, 2016/04/06 08:43:17]

Done; added the field in_idle_period_for_testing to struct MainThreadOnly in
RendererSchedulerImp.

+  idle_queue_->PumpQueue(true);
+}
+
 }  // namespace scheduler