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

components/scheduler/child/idle_helper.h

 // 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.
 
 #ifndef COMPONENTS_SCHEDULER_CHILD_IDLE_HELPER_H_
 #define COMPONENTS_SCHEDULER_CHILD_IDLE_HELPER_H_
 
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
 #include "components/scheduler/base/cancelable_closure_holder.h"
@@ skipping 106 matching lines @@
   base::TimeTicks WillProcessIdleTask() override;
   void DidProcessIdleTask() override;
 
   // base::MessageLoop::TaskObserver implementation:
   void WillProcessTask(const base::PendingTask& pending_task) override;
   void DidProcessTask(const base::PendingTask& pending_task) override;
 
   IdlePeriodState SchedulerIdlePeriodState() const;
   static const char* IdlePeriodStateToString(IdlePeriodState state);
 
+  // Test helper
+  void RunIdleTasksForTesting(const base::Closure&);

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

In this implementation all the idle callbacks are basically getting given a 0 ms
time slice to do their work, right? I think we should make that an explicit
parameter here.

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

I changed the implementation to use a regular long idle period, so the tasks
will get a time slice based on the standard long idle period deadline.

+
  private:
   friend class BaseIdleHelperTest;
   friend class IdleHelperTest;
 
   class State {
    public:
     State(SchedulerHelper* helper,
           Delegate* delegate,
           const char* tracing_category,
           const char* disabled_by_default_tracing_category,
@@ skipping 75 matching lines @@
 
   base::WeakPtr<IdleHelper> weak_idle_helper_ptr_;
   base::WeakPtrFactory<IdleHelper> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(IdleHelper);
 };
 
 }  // namespace scheduler
 
 #endif  // COMPONENTS_SCHEDULER_CHILD_IDLE_HELPER_H_