cc: Remove ScheduleOnOriginThread() and CompleteOnOriginThread().

cc/tiles/software_image_decode_controller.cc

Index: cc/tiles/software_image_decode_controller.cc
diff --git a/cc/tiles/software_image_decode_controller.cc b/cc/tiles/software_image_decode_controller.cc
index 8ed5a0eb4e33fdaf94e30d8daedb76c8e30019b5..6c8bbd7a2720e586c4a1a6cb073718f7adc4a0bd 100644
--- a/cc/tiles/software_image_decode_controller.cc
+++ b/cc/tiles/software_image_decode_controller.cc
@@ -64,7 +64,9 @@ class ImageDecodeTaskImpl : public ImageDecodeTask {
         image_key_(image_key),
         image_(image),
         image_ref_(skia::SharePtr(image.image())),
-        source_prepare_tiles_id_(source_prepare_tiles_id) {}
+        source_prepare_tiles_id_(source_prepare_tiles_id) {
+    SetTaskTypeId(TASK_TYPE_IMAGE_DECODE);
+  }
 
   // Overridden from Task:
   void RunOnWorkerThread() override {
@@ -76,22 +78,17 @@ class ImageDecodeTaskImpl : public ImageDecodeTask {
     controller_->DecodeImage(image_key_, image_);
   }
 
-  // Overridden from TileTask:
-  void ScheduleOnOriginThread(TileTaskClient* client) override {}
-  void CompleteOnOriginThread(TileTaskClient* client) override {
-    controller_->RemovePendingTask(image_key_);
-  }
-
  protected:
   ~ImageDecodeTaskImpl() override {}
 
- private:
+ public:
   SoftwareImageDecodeController* controller_;
   SoftwareImageDecodeController::ImageKey image_key_;
   DrawImage image_;
   skia::RefPtr<const SkImage> image_ref_;
   uint64_t source_prepare_tiles_id_;
 
+ private:
   DISALLOW_COPY_AND_ASSIGN(ImageDecodeTaskImpl);
 };
 
@@ -688,6 +685,12 @@ void SoftwareImageDecodeController::ReduceCacheUsage() {
   }
 }
 
+void SoftwareImageDecodeController::ImageDecodeTaskCompleted(Task* task) {
+  ImageDecodeTaskImpl* decode_task = static_cast<ImageDecodeTaskImpl*>(task);
+  DCHECK(decode_task);
+  RemovePendingTask(decode_task->image_key_);
+}
+
 void SoftwareImageDecodeController::RemovePendingTask(const ImageKey& key) {
   base::AutoLock lock(lock_);
   pending_image_tasks_.erase(key);