content: Implement dynamic priorities for raster threads.

content/renderer/raster_worker_pool.h

Index: content/renderer/raster_worker_pool.h
diff --git a/content/renderer/raster_worker_pool.h b/content/renderer/raster_worker_pool.h
index b4ddf9a61c251e6f759400ccff94266941a2f604..e26d6ed5cccc482450da6dfbf85a14e06abdc6d5 100644
--- a/content/renderer/raster_worker_pool.h
+++ b/content/renderer/raster_worker_pool.h
@@ -29,7 +29,8 @@ namespace content {
 // It's also possible to get the underlying TaskGraphRunner to schedule a graph
 // of tasks with their dependencies.
 class CONTENT_EXPORT RasterWorkerPool : public base::TaskRunner,
-                                        public cc::TaskGraphRunner {
+                                        public cc::TaskGraphRunner,
+                                        public cc::TaskGraphWorkQueueClient {
  public:
   RasterWorkerPool();
 
@@ -46,9 +47,17 @@ class CONTENT_EXPORT RasterWorkerPool : public base::TaskRunner,
   void CollectCompletedTasks(cc::NamespaceToken token,
                              cc::Task::Vector* completed_tasks) override;
 
+  // TODO(prashant.n): Move this to separate class to control workers
+  // efficiently.
+  // Overridden from cc::TaskGraphWorkQueueClient:
+  void AdjustWorkerPriorityForTask(cc::Task* task,
+                                   uint16_t old_category,
+                                   uint16_t new_category) override;
+
   // Runs a task from one of the provided categories. Categories listed first
   // have higher priority.
-  void Run(const std::vector<cc::TaskCategory>& categories,
+  void Run(cc::TaskWorker* worker,
+           const std::vector<cc::TaskCategory>& categories,
            base::ConditionVariable* has_ready_to_run_tasks_cv);
 
   void FlushForTesting();
@@ -101,11 +110,13 @@ class CONTENT_EXPORT RasterWorkerPool : public base::TaskRunner,
 
   // Runs a task from one of the provided categories. Categories listed first
   // have higher priority. Returns false if there were no tasks to run.
-  bool RunTaskWithLockAcquired(const std::vector<cc::TaskCategory>& categories);
+  bool RunTaskWithLockAcquired(cc::TaskWorker* worker,
+                               const std::vector<cc::TaskCategory>& categories);
 
   // Run next task for the given category. Caller must acquire |lock_| prior to
   // calling this function and make sure at least one task is ready to run.
-  void RunTaskInCategoryWithLockAcquired(cc::TaskCategory category);
+  void RunTaskInCategoryWithLockAcquired(cc::TaskWorker* worker,
+                                         cc::TaskCategory category);
 
   // Helper function which signals worker threads if tasks are ready to run.
   void SignalHasReadyToRunTasksWithLockAcquired();
@@ -116,7 +127,7 @@ class CONTENT_EXPORT RasterWorkerPool : public base::TaskRunner,
   bool ShouldRunTaskForCategoryWithLockAcquired(cc::TaskCategory category);
 
   // The actual threads where work is done.
-  std::vector<scoped_ptr<base::SimpleThread>> threads_;
+  std::vector<scoped_ptr<base::DynamicPriorityThread>> threads_;
 
   // Lock to exclusively access all the following members that are used to
   // implement the TaskRunner and TaskGraphRunner interfaces.