Introduce a SchedulerHelper in content/child/scheduler

content/child/scheduler/single_thread_idle_task_runner.cc

 // Copyright 2014 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 "content/renderer/scheduler/single_thread_idle_task_runner.h"
+#include "content/child/scheduler/single_thread_idle_task_runner.h"
 
 #include "base/location.h"
 #include "base/trace_event/trace_event.h"
 
 namespace content {
 
 SingleThreadIdleTaskRunner::SingleThreadIdleTaskRunner(
     scoped_refptr<base::SingleThreadTaskRunner> idle_priority_task_runner,
     scoped_refptr<base::SingleThreadTaskRunner> after_wakeup_task_runner,
-    base::Callback<void(base::TimeTicks*)> deadline_supplier)
+    base::Callback<void(base::TimeTicks*)> deadline_supplier,
+    const char* tracing_category)
     : idle_priority_task_runner_(idle_priority_task_runner),
       after_wakeup_task_runner_(after_wakeup_task_runner),
-      deadline_supplier_(deadline_supplier) {
+      deadline_supplier_(deadline_supplier),
+      tracing_category_(tracing_category),
+      weak_factory_(this) {
   DCHECK(!idle_priority_task_runner_ ||
          idle_priority_task_runner_->RunsTasksOnCurrentThread());
   DCHECK(!after_wakeup_task_runner_ ||
          after_wakeup_task_runner_->RunsTasksOnCurrentThread());
+  weak_scheduler_ptr_ = weak_factory_.GetWeakPtr();
 }
 
 SingleThreadIdleTaskRunner::~SingleThreadIdleTaskRunner() {
 }
 
 bool SingleThreadIdleTaskRunner::RunsTasksOnCurrentThread() const {
   return idle_priority_task_runner_->RunsTasksOnCurrentThread();
 }
 
 void SingleThreadIdleTaskRunner::PostIdleTask(
     const tracked_objects::Location& from_here,
     const IdleTask& idle_task) {
   idle_priority_task_runner_->PostTask(
       from_here,
-      base::Bind(&SingleThreadIdleTaskRunner::RunTask, this, idle_task));
+      base::Bind(&SingleThreadIdleTaskRunner::RunTask,
+                 weak_scheduler_ptr_, idle_task));
 }
 
 void SingleThreadIdleTaskRunner::PostNonNestableIdleTask(
     const tracked_objects::Location& from_here,
     const IdleTask& idle_task) {
   idle_priority_task_runner_->PostNonNestableTask(
       from_here,
-      base::Bind(&SingleThreadIdleTaskRunner::RunTask, this, idle_task));
+      base::Bind(&SingleThreadIdleTaskRunner::RunTask,
+                 weak_scheduler_ptr_, idle_task));
 }
 
 void SingleThreadIdleTaskRunner::PostIdleTaskAfterWakeup(
     const tracked_objects::Location& from_here,
     const IdleTask& idle_task) {
   after_wakeup_task_runner_->PostTask(
-      FROM_HERE, base::Bind(&SingleThreadIdleTaskRunner::PostIdleTask, this,
-                            from_here, idle_task));
+      FROM_HERE, base::Bind(&SingleThreadIdleTaskRunner::PostIdleTask,
+                            weak_scheduler_ptr_, from_here, idle_task));
 }
 
 void SingleThreadIdleTaskRunner::RunTask(IdleTask idle_task) {
   base::TimeTicks deadline;
   deadline_supplier_.Run(&deadline);
-  TRACE_EVENT1("renderer.scheduler",
-               "SingleThreadIdleTaskRunner::RunTask", "allotted_time_ms",
+  TRACE_EVENT1(tracing_category_, "SingleThreadIdleTaskRunner::RunTask",
+               "allotted_time_ms",
                (deadline - base::TimeTicks::Now()).InMillisecondsF());
   idle_task.Run(deadline);
   bool is_tracing;
-  TRACE_EVENT_CATEGORY_GROUP_ENABLED("renderer.scheduler", &is_tracing);
+  TRACE_EVENT_CATEGORY_GROUP_ENABLED(tracing_category_, &is_tracing);
   if (is_tracing && base::TimeTicks::Now() > deadline) {
-    TRACE_EVENT_INSTANT0("renderer.scheduler",
+    TRACE_EVENT_INSTANT0(tracing_category_,
                          "SingleThreadIdleTaskRunner::DidOverrunDeadline",
                          TRACE_EVENT_SCOPE_THREAD);
   }
 }
 
 }  // namespace content