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 93d017f186fa0dd34000ca815ef3f7ff637cdc17..916365365563d072e834a415acae517f9407d644 100644
--- a/cc/tiles/software_image_decode_controller.cc
+++ b/cc/tiles/software_image_decode_controller.cc
@@ -71,15 +71,12 @@ class ImageDecodeTaskImpl : public ImageDecodeTask {
     controller_->DecodeImage(image_key_, image_);
   }
 
-  // Overridden from TileTask:
-  void ScheduleOnOriginThread(TileTaskClient* client) override {}
-  void CompleteOnOriginThread(TileTaskClient* client) override {
+ protected:
+  ~ImageDecodeTaskImpl() override {
     controller_->RemovePendingTask(image_key_);

[prashant.n, 2016/04/08 16:38:39]

By moving this code from CompleteOnOriginThread() hurts current logic of
GetTaskForImageAndRef().

browser runs well, but unittests crashes.

ericrk@, vmpstr@,

Is it okay to move this functionality to dtor? If yes I'll try to modify the
logic to take care of this change.

[vmpstr, 2016/04/08 18:59:16]

No, this doesn't work. The task is kept alive by the pending tasks on the
controller, so one of two things is true:

1. Either this dtor will never be called, or
2. This call will not do anything since there are no references.

I think you might end up leaking things.

Basically, if the task decoded the image then it will have removed itself from
the pending set. However, if the task was cancelled then there is nothing to
remove it from the pending set and this ctor will never be called. 

+    LOG(ERROR) << "PRAS2::" << __FUNCTION__;
   }
 
- protected:
-  ~ImageDecodeTaskImpl() override {}
-
  private:
   SoftwareImageDecodeController* controller_;
   SoftwareImageDecodeController::ImageKey image_key_;
@@ -219,6 +216,7 @@ bool SoftwareImageDecodeController::GetTaskForImageAndRef(
   // If the task exists, return it.
   scoped_refptr<ImageDecodeTask>& existing_task = pending_image_tasks_[key];
   if (existing_task) {
+    LOG(ERROR) << "PRAS::existing " << __FUNCTION__;
     RefImage(key);
     *task = existing_task;
     SanityCheckState(__LINE__, true);
@@ -243,6 +241,7 @@ bool SoftwareImageDecodeController::GetTaskForImageAndRef(
   existing_task = make_scoped_refptr(
       new ImageDecodeTaskImpl(this, key, image, prepare_tiles_id));
   *task = existing_task;
+  LOG(ERROR) << "PRAS::new " << __FUNCTION__;
   SanityCheckState(__LINE__, true);
   return true;
 }