Add a few extra tests for throttling corner cases

components/scheduler/renderer/throttling_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_RENDERER_THROTTLING_HELPER_H_
 #define COMPONENTS_SCHEDULER_RENDERER_THROTTLING_HELPER_H_
 
 #include <set>
 
 #include "base/macros.h"
@@ skipping 12 matching lines @@
  public:
   ThrottlingHelper(RendererSchedulerImpl* renderer_scheduler,
                    const char* tracing_category);
 
   ~ThrottlingHelper() override;
 
   // TimeDomain::Observer implementation:
   void OnTimeDomainHasImmediateWork() override;
   void OnTimeDomainHasDelayedWork() override;
 
-  // The purpose of this method is to make sure thottling doesn't conflict with
+  // The purpose of this method is to make sure throttling doesn't conflict with
   // enabling/disabling the queue for policy reasons.
   // If |task_queue| is throttled then the ThrottlingHelper remembers the
   // |enabled| setting.  In addition if |enabled| is false then the queue is
   // immediatly disabled.  Otherwise if |task_queue| not throttled then
   // TaskQueue::SetEnabled(enabled) is called.
   void SetQueueEnabled(TaskQueue* task_queue, bool enabled);
 
   // Increments the throttled refcount and causes |task_queue| to be throttled
   // if its not already throttled.
   void IncreaseThrottleRefCount(TaskQueue* task_queue);
@@ skipping 46 matching lines @@
   base::TimeTicks pending_pump_throttled_tasks_runtime_;
 
   base::WeakPtrFactory<ThrottlingHelper> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ThrottlingHelper);
 };
 
 }  // namespace scheduler
 
 #endif  // COMPONENTS_SCHEDULER_RENDERER_THROTTLING_HELPER_H_