cc: Remove ScheduleOnOriginThread() and CompleteOnOriginThread().

cc/raster/task.h

 // 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.
 
 #ifndef CC_RASTER_TASK_H_
 #define CC_RASTER_TASK_H_
 
 #include <stdint.h>
 
 #include <vector>
 
 #include "base/memory/ref_counted.h"
 #include "cc/base/cc_export.h"
 
 namespace cc {
 class Task;
 
 // States to manage life cycle of a task. Task gets created with NEW state and
-// concludes either in FINISHED or CANCELLED state. So possible life cycle
-// paths for task are -
-//   NEW -> SCHEDULED -> RUNNING -> FINISHED
-//   NEW -> SCHEDULED -> CANCELED
+// if scheduled concludes in COMPLETED state. So possible life cycle paths for

[vmpstr, 2016/05/18 19:08:33]

you say here "if scheduled concludes in completed" but below you have an example
of NEW -> CANCELED -> COMPLETED. That seems contradictory. 

[prashant.n, 2016/05/19 00:59:52]

This above path is for task which is not scheduled (has dependecies), but
cancelled due to reschedule. Actually task scheduled means added to
|ready_to_run_tasks|.

+// task are -
+//   NEW

[vmpstr, 2016/05/18 19:08:33]

I don't think you need this one?

[prashant.n, 2016/05/19 00:59:52]

We will omit this.

+//   NEW -> CANCELED -> COMPLETED
+//   NEW -> SCHEDULED -> CANCELED-> COMPLETED
+//   NEW -> SCHEDULED -> RUNNING -> FINISHED -> COMPLETED
 class CC_EXPORT TaskState {
  public:
   bool IsScheduled() const;
   bool IsRunning() const;
   bool IsFinished() const;
   bool IsCanceled() const;
+  bool IsCompleted() const;
 
   // Functions to change the state of task. These functions should be called
   // only from TaskGraphWorkQueue where the life cycle of a task is decided or
   // from tests. These functions are not thread-safe. Caller is responsible for
   // thread safety.
   void Reset();  // Sets state to NEW.
   void DidSchedule();
   void DidStart();
   void DidFinish();
   void DidCancel();
 
+  // Task owner should call this function to indicate that this task is
+  // completed and no more it should be processed.

[vmpstr, 2016/05/18 19:08:33]

s/no more it should be processed/it doesn't need to be processed anymore/

[prashant.n, 2016/05/19 00:59:52]

Ok, I'll modify this.

+  void DidComplete();
+
  private:
   friend class Task;
 
   // Let only Task class create the TaskState.
   TaskState();
   ~TaskState();
 
-  enum class Value : uint16_t { NEW, SCHEDULED, RUNNING, FINISHED, CANCELED };
+  enum class Value : uint16_t {
+    NEW,
+    SCHEDULED,
+    RUNNING,
+    FINISHED,
+    CANCELED,
+    COMPLETED

[vmpstr, 2016/05/18 19:08:33]

In my mind the difference between "FINISHED" and "COMPLETED" is very small... I
think we either need to come up with a different name or... somethign

[prashant.n, 2016/05/19 00:59:52]

Yes. Finished and Completed are 2 sides of same coin. Finished is by task graph
runner and Completed is by task owner (e.g. tile manager). It just for
semantics.

Ideally finished tasks get skipped while sheduling. And as we ensure checking
completed tasks before TileManager::ScheduleTask(), Completed looks redundant,
we can use finished state there.

I'll revisit this and remove Completed if redundant.

+  };
 
   Value value_;
 };
 
 // A task which can be run by a TaskGraphRunner. To run a Task, it should be
 // inserted into a TaskGraph, which can then be scheduled on the
 // TaskGraphRunner.
 class CC_EXPORT Task : public base::RefCountedThreadSafe<Task> {
  public:
   typedef std::vector<scoped_refptr<Task>> Vector;
@@ skipping 59 matching lines @@
   void Swap(TaskGraph* other);
   void Reset();
 
   Node::Vector nodes;
   Edge::Vector edges;
 };
 
 }  // namespace cc
 
 #endif  // CC_RASTER_TASK_H_