cc: Rasterize cheap tiles immediately

cc/worker_pool.h

 // Copyright 2013 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 CC_WORKER_POOL_H_
 #define CC_WORKER_POOL_H_
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "base/cancelable_callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/threading/thread.h"
 #include "cc/rendering_stats.h"
 #include "cc/scoped_ptr_deque.h"
 
 namespace cc {
 namespace internal {
 
 class WorkerPoolTask {
  public:
   virtual ~WorkerPoolTask();
 
+  // Called when the task is scheduled to run on a thread that isn't the
+  // origin thread.
+  virtual void WillRunOnThread(base::Thread* thread) = 0;
+
   virtual void Run(RenderingStats* rendering_stats) = 0;
 
   bool HasCompleted();
   void DidComplete();
 
  protected:
   WorkerPoolTask(const base::Closure& reply);
 
   const base::Closure reply_;
 
@@ skipping 78 matching lines @@
 
     WorkerPool* worker_pool_;
     ScopedPtrDeque<internal::WorkerPoolTask> pending_tasks_;
     scoped_ptr<RenderingStats> rendering_stats_;
     bool record_rendering_stats_;
   };
 
   WorkerPool(WorkerPoolClient* client, size_t num_threads);
 
   WorkerPool::Worker* GetWorkerForNextTask();
+  bool CanPostCheapTask() const;
+  void PostCheapTask(scoped_ptr<internal::WorkerPoolTask> task);
 
  private:
   class NumPendingTasksComparator {
    public:
     bool operator() (const Worker* a, const Worker* b) const {
       return a->num_pending_tasks() < b->num_pending_tasks();
     }
   };
 
   // Schedule a completed tasks check if not already pending.
@@ skipping 10 matching lines @@
 
   // Check for completed tasks and run reply callbacks.
   void CheckForCompletedTasks();
 
   // Called when processing task completion.
   void OnTaskCompleted();
 
   // Ensure workers are sorted by number of pending tasks.
   void SortWorkersIfNeeded();
 
+  // Schedule running cheap tasks on the origin thread unless already pending.
+  void ScheduleRunCheapTasks();
+
+  // Run pending cheap tasks on the origin thread. If the allotted time slot
+  // for cheap tasks runs out, the remaining tasks are deferred to the thread
+  // pool.
+  void RunCheapTasks();
+
   typedef std::vector<Worker*> WorkerVector;
   WorkerVector workers_;
   WorkerPoolClient* client_;
   scoped_refptr<base::MessageLoopProxy> origin_loop_;
   base::WeakPtrFactory<WorkerPool> weak_ptr_factory_;
   bool workers_need_sorting_;
   bool shutdown_;
   base::CancelableClosure check_for_completed_tasks_callback_;
-  bool check_for_completed_tasks_pending_;
+  base::TimeTicks check_for_completed_tasks_deadline_;
   base::Closure idle_callback_;
+  base::Closure cheap_task_callback_;
   // Accessed from multiple threads. 0 when worker pool is idle.
   base::subtle::Atomic32 pending_task_count_;
 
+  bool run_cheap_tasks_pending_;
+  ScopedPtrDeque<internal::WorkerPoolTask> pending_cheap_tasks_;
+  ScopedPtrDeque<internal::WorkerPoolTask> completed_cheap_tasks_;
+  scoped_ptr<RenderingStats> cheap_rendering_stats_;
+
   DISALLOW_COPY_AND_ASSIGN(WorkerPool);
 };
 
 }  // namespace cc
 
 #endif  // CC_WORKER_POOL_H_