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 3f52af5c1989e40e5c5d3064109bd7d65b023a7b..abdb60b8013e392fd8eeed759bc949e45b1787cb 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(kImageDecodeTaskTypeId);
+  }
 
   // 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);
 };
 
@@ -630,6 +627,12 @@ void SoftwareImageDecodeController::DrawWithImageFinished(
   SanityCheckState(__LINE__, false);
 }
 
+void SoftwareImageDecodeController::CompleteTask(Task* task) {
+  ImageDecodeTaskImpl* decode_task = static_cast<ImageDecodeTaskImpl*>(task);
+  DCHECK(decode_task);
+  RemovePendingTask(decode_task->image_key_);
+}
+
 void SoftwareImageDecodeController::RefAtRasterImage(const ImageKey& key) {
   TRACE_EVENT1("disabled-by-default-cc.debug",
                "SoftwareImageDecodeController::RefAtRasterImage", "key",