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 263720d79f53ebd965a754afb47a48b18ff5db8b..70ed3f86a2642972dbcbb0a0ea4c690074b53c94 100644
--- a/cc/raster/tile_task_worker_pool.cc
+++ b/cc/raster/tile_task_worker_pool.cc
@@ -20,14 +20,15 @@ TileTaskWorkerPool::TileTaskWorkerPool() {}
 TileTaskWorkerPool::~TileTaskWorkerPool() {}
 
 // static
-void TileTaskWorkerPool::ScheduleTasksOnOriginThread(TileTaskClient* client,
-                                                     TaskGraph* graph) {
+void TileTaskWorkerPool::ScheduleTasksOnOriginThread(
+    DependencyTaskClient* client,
+    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);
+    DependencyTask* task = node.task;
 
     if (!task->HasBeenScheduled()) {
       task->WillSchedule();