cc: Remove ScheduleOnOriginThread() and CompleteOnOriginThread().

cc/raster/bitmap_tile_task_worker_pool.cc

Index: cc/raster/bitmap_tile_task_worker_pool.cc
diff --git a/cc/raster/bitmap_tile_task_worker_pool.cc b/cc/raster/bitmap_tile_task_worker_pool.cc
index a24b1a23b13d3ac9f1ee89b5b01a06fb524e1564..9800e12f9f33b3b6661da82fb5c1b6f87f853795 100644
--- a/cc/raster/bitmap_tile_task_worker_pool.cc
+++ b/cc/raster/bitmap_tile_task_worker_pool.cc
@@ -103,24 +103,14 @@ void BitmapTileTaskWorkerPool::Shutdown() {
 void BitmapTileTaskWorkerPool::ScheduleTasks(TaskGraph* graph) {
   TRACE_EVENT0("cc", "BitmapTileTaskWorkerPool::ScheduleTasks");
 
-  ScheduleTasksOnOriginThread(this, graph);
   task_graph_runner_->ScheduleTasks(namespace_token_, graph);
 }
 
-void BitmapTileTaskWorkerPool::CheckForCompletedTasks() {
+void BitmapTileTaskWorkerPool::CollectCompletedTasks(
+    Task::Vector* completed_tasks) {
   TRACE_EVENT0("cc", "BitmapTileTaskWorkerPool::CheckForCompletedTasks");
 
-  task_graph_runner_->CollectCompletedTasks(namespace_token_,
-                                            &completed_tasks_);
-  for (Task::Vector::const_iterator it = completed_tasks_.begin();
-       it != completed_tasks_.end(); ++it) {
-    TileTask* task = static_cast<TileTask*>(it->get());
-
-    task->WillComplete();
-    task->CompleteOnOriginThread(this);
-    task->DidComplete();
-  }
-  completed_tasks_.clear();
+  task_graph_runner_->CollectCompletedTasks(namespace_token_, completed_tasks);
 }
 
 ResourceFormat BitmapTileTaskWorkerPool::GetResourceFormat(
@@ -133,6 +123,10 @@ bool BitmapTileTaskWorkerPool::GetResourceRequiresSwizzle(
   return ResourceFormatRequiresSwizzle(GetResourceFormat(must_support_alpha));
 }
 
+TileTaskClient* BitmapTileTaskWorkerPool::AsTileTaskClient() {
+  return this;
+}
+
 std::unique_ptr<RasterBuffer> BitmapTileTaskWorkerPool::AcquireBufferForRaster(
     const Resource* resource,
     uint64_t resource_content_id,