cc: Simplify Task and its derived classes.

cc/raster/tile_task_runner.cc

-// Copyright 2014 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.
-
-#include "cc/raster/tile_task_runner.h"
-
-namespace cc {
-
-TileTask::TileTask() : did_complete_(false) {}
-
-TileTask::~TileTask() {
-  DCHECK(!did_run_ || did_complete_);
-}
-
-void TileTask::DidComplete() {
-  DCHECK(!did_complete_);
-  did_complete_ = true;
-}
-
-bool TileTask::HasCompleted() const {
-  return did_complete_;
-}
-
-ImageDecodeTask::ImageDecodeTask() {
-}
-
-ImageDecodeTask::ImageDecodeTask(scoped_refptr<ImageDecodeTask> dependency)
-    : dependency_(std::move(dependency)) {}
-
-ImageDecodeTask::~ImageDecodeTask() {
-}
-
-bool ImageDecodeTask::SupportsConcurrentExecution() const {
-  return true;
-}
-
-RasterTask::RasterTask(ImageDecodeTask::Vector* dependencies) {
-  dependencies_.swap(*dependencies);
-}
-
-RasterTask::~RasterTask() {
-}
-
-}  // namespace cc