cc: Simplify task and its derived classes.

cc/raster/tile_task_worker_pool.cc

Index: cc/raster/tile_task_worker_pool.cc
diff --git a/cc/raster/tile_task_worker_pool.cc b/cc/raster/tile_task_worker_pool.cc
index 510862af1f141d6faeafc803094b31268c14d6d1..2c806658fa8d2ac9743c66cc86cda6f12a43d848 100644
--- a/cc/raster/tile_task_worker_pool.cc
+++ b/cc/raster/tile_task_worker_pool.cc
@@ -20,18 +20,17 @@ TileTaskWorkerPool::TileTaskWorkerPool() {}
 TileTaskWorkerPool::~TileTaskWorkerPool() {}
 
 // static
-void TileTaskWorkerPool::ScheduleTasksOnOriginThread(TileTaskClient* client,
-                                                     TaskGraph* graph) {
+void TileTaskWorkerPool::ScheduleTasksOnOriginThread(TaskGraph* graph) {
   TRACE_EVENT0("cc", "TileTaskWorkerPool::ScheduleTasksOnOriginThread");
 
   for (TaskGraph::Node::Vector::iterator it = graph->nodes.begin();
        it != graph->nodes.end(); ++it) {
     TaskGraph::Node& node = *it;
-    TileTask* task = static_cast<TileTask*>(node.task);
+    Task* task = node.task;
 
     if (!task->HasBeenScheduled()) {
       task->WillSchedule();
-      task->ScheduleOnOriginThread(client);
+      task->ScheduleOnOriginThread();
       task->DidSchedule();
     }
   }