cc: Simplify task and its derived classes.

cc/tiles/gpu_image_decode_controller.cc

 // Copyright 2016 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/tiles/gpu_image_decode_controller.h"
 
 #include "cc/debug/devtools_instrumentation.h"
 #include "cc/raster/tile_task_runner.h"
 #include "skia/ext/refptr.h"
 
 namespace cc {
 
-class ImageDecodeTaskImpl : public ImageDecodeTask {
+class ImageDecodeTaskImpl : public Task {
  public:
   ImageDecodeTaskImpl(GpuImageDecodeController* controller,
                       const DrawImage& image,
                       uint64_t source_prepare_tiles_id)
       : controller_(controller),
         image_(image),
         image_ref_(skia::SharePtr(image.image())),
         source_prepare_tiles_id_(source_prepare_tiles_id) {}
 
   // Overridden from Task:
+  void ScheduleOnOriginThread() override {}
+  void CompleteOnOriginThread() override {
+    controller_->RemovePendingTaskForImage(image_);
+  }
   void RunOnWorkerThread() override {
     TRACE_EVENT2("cc", "ImageDecodeTaskImpl::RunOnWorkerThread", "mode", "gpu",
                  "source_prepare_tiles_id", source_prepare_tiles_id_);
     devtools_instrumentation::ScopedImageDecodeTask image_decode_task(
         image_ref_.get());
     controller_->DecodeImage(image_);
   }
 
-  // Overridden from TileTask:
-  void ScheduleOnOriginThread(TileTaskClient* client) override {}
-  void CompleteOnOriginThread(TileTaskClient* client) override {
-    controller_->RemovePendingTaskForImage(image_);
-  }
-
  protected:
   ~ImageDecodeTaskImpl() override {}
 
  private:
   GpuImageDecodeController* controller_;
   DrawImage image_;
   skia::RefPtr<const SkImage> image_ref_;
   uint64_t source_prepare_tiles_id_;
 
   DISALLOW_COPY_AND_ASSIGN(ImageDecodeTaskImpl);
 };
 
 GpuImageDecodeController::GpuImageDecodeController() {}
 
 GpuImageDecodeController::~GpuImageDecodeController() {}
 
 bool GpuImageDecodeController::GetTaskForImageAndRef(
     const DrawImage& image,
     uint64_t prepare_tiles_id,
-    scoped_refptr<ImageDecodeTask>* task) {
+    scoped_refptr<Task>* task) {
   auto image_id = image.image()->uniqueID();
   base::AutoLock lock(lock_);
   if (prerolled_images_.count(image_id) != 0) {
     *task = nullptr;
     return false;
   }
 
-  scoped_refptr<ImageDecodeTask>& existing_task =
-      pending_image_tasks_[image_id];
+  scoped_refptr<Task>& existing_task = pending_image_tasks_[image_id];
   if (!existing_task) {
     existing_task = make_scoped_refptr(
         new ImageDecodeTaskImpl(this, image, prepare_tiles_id));
   }
   *task = existing_task;
   return false;
 }
 
 void GpuImageDecodeController::UnrefImage(const DrawImage& image) {
   NOTREACHED();
@@ skipping 16 matching lines @@
   prerolled_images_.insert(image.image()->uniqueID());
 }
 
 void GpuImageDecodeController::RemovePendingTaskForImage(
     const DrawImage& image) {
   base::AutoLock lock(lock_);
   pending_image_tasks_.erase(image.image()->uniqueID());
 }
 
 }  // namespace cc