cc: Simplify Task and its derived classes.

cc/raster/tile_task_runner.h

Index: cc/raster/tile_task_runner.h
diff --git a/cc/raster/tile_task_runner.h b/cc/raster/tile_task_runner.h
index dc1586a606b5ebc541ffc000279bcc1514c6936e..04f81894385719eedc7735737aa3584a36dd3590 100644
--- a/cc/raster/tile_task_runner.h
+++ b/cc/raster/tile_task_runner.h
@@ -11,7 +11,7 @@
 
 #include "base/callback.h"
 #include "cc/raster/raster_buffer.h"
-#include "cc/raster/task_graph_runner.h"
+#include "cc/raster/task.h"
 #include "cc/resources/resource_format.h"
 
 namespace cc {
@@ -20,6 +20,14 @@ class CC_EXPORT TileTask : public Task {
  public:
   typedef std::vector<scoped_refptr<TileTask>> Vector;
 
+  const TileTask::Vector& dependencies() const { return dependencies_; }
+
+  // Indicates whether this TileTask can be run at the same time as other tasks
+  // in the task graph. If false, this task will be scheduled with
+  // TASK_CATEGORY_NONCONCURRENT_FOREGROUND. The base implementation always
+  // returns true.
+  virtual bool SupportsConcurrentExecution() const;

[reveman, 2016/04/19 00:05:30]

can this be a implemented using a "const bool supports_concurrent_execution_;"
member instead that is set by the ctor? and exposed using a simple
supports_concurrent_execution() getter..

[prashant.n, 2016/04/19 01:19:02]

Yes.

+
   virtual void ScheduleOnOriginThread(RasterBufferProvider* provider) = 0;
   virtual void CompleteOnOriginThread(RasterBufferProvider* provider) = 0;
 
@@ -33,48 +41,14 @@ class CC_EXPORT TileTask : public Task {
 
  protected:
   TileTask();
+  explicit TileTask(TileTask::Vector* dependencies);
   ~TileTask() override;
 
+  TileTask::Vector dependencies_;
   bool did_schedule_;
   bool did_complete_;
 };
 
-class CC_EXPORT ImageDecodeTask : public TileTask {
- public:
-  typedef std::vector<scoped_refptr<ImageDecodeTask>> Vector;
-
-  // Indicates whether this ImageDecodeTask can be run at the same time as
-  // other tasks in the task graph. If false, this task will be scheduled with
-  // TASK_CATEGORY_NONCONCURRENT_FOREGROUND. The base implementation always
-  // returns true.
-  virtual bool SupportsConcurrentExecution() const;
-
-  // Returns an optional task which this task depends on. May be null.
-  const scoped_refptr<ImageDecodeTask>& dependency() { return dependency_; }
-
- protected:
-  ImageDecodeTask();
-  explicit ImageDecodeTask(scoped_refptr<ImageDecodeTask> dependency);
-  ~ImageDecodeTask() override;
-
- private:
-  scoped_refptr<ImageDecodeTask> dependency_;
-};
-
-class CC_EXPORT RasterTask : public TileTask {
- public:
-  typedef std::vector<scoped_refptr<RasterTask>> Vector;
-
-  const ImageDecodeTask::Vector& dependencies() const { return dependencies_; }
-
- protected:
-  explicit RasterTask(ImageDecodeTask::Vector* dependencies);
-  ~RasterTask() override;
-
- private:
-  ImageDecodeTask::Vector dependencies_;
-};
-
 // This interface can be used to schedule and run tile tasks.
 // The client can call CheckForCompletedTasks() at any time to dispatch
 // pending completion callbacks for all tasks that have finished running.