cc: Merge TileTaskRunner to TileTaskWorkerPool.

cc/raster/tile_task_worker_pool.h

 // Copyright 2013 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_TILE_TASK_WORKER_POOL_H_
 #define CC_RASTER_TILE_TASK_WORKER_POOL_H_
 
 #include <stddef.h>
 
 #include "cc/playback/raster_source.h"
 #include "cc/raster/task_graph_runner.h"
-#include "cc/raster/tile_task_runner.h"
+#include "cc/raster/tile_task.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/size.h"
 
 namespace base {
 class SequencedTaskRunner;
 }
 
 namespace cc {
 class RenderingStatsInstrumentation;
 
+// This class provides the wrapper over TaskGraphRunner for scheduling and
+// collecting tasks. The client can call CheckForCompletedTasks() at any time to
+// process all completed tasks at the moment that have finished running or
+// cancelled.
 class CC_EXPORT TileTaskWorkerPool {

[ericrk, 2016/04/20 00:22:29]

I wonder if this should be called TileTaskRunner, and we should just get rid of
the name TileTaskWorkerPool - runner seems more descriptive of what the
interface does - WDYT? Either way, feel free to deal with this in a separate CL.

[prashant.n, 2016/04/20 02:04:48]

I was thinking to call this as TileTaskController or just TileTaskWorker as it
is raster buffer provider + wrapper over tile graph runner.

[prashant.n, 2016/04/20 04:16:12]

As David suggested, we should get rid of TileTaskWorkerPool and have different
implementations of RasterBufferProviders.

  public:
   TileTaskWorkerPool();
   virtual ~TileTaskWorkerPool();
 
   // Utility function that can be used to call ::ScheduleOnOriginThread() for
   // each task in |graph|.
   static void ScheduleTasksOnOriginThread(RasterBufferProvider* provider,
                                           TaskGraph* graph);
 
   // Utility function that will create a temporary bitmap and copy pixels to
   // |memory| when necessary. The |canvas_bitmap_rect| is the rect of the bitmap
   // being played back in the pixel space of the source, ie a rect in the source
   // that will cover the resulting |memory|. The |canvas_playback_rect| can be a
   // smaller contained rect inside the |canvas_bitmap_rect| if the |memory| is
   // already partially complete, and only the subrect needs to be played back.
   static void PlaybackToMemory(
       void* memory,
       ResourceFormat format,
       const gfx::Size& size,
       size_t stride,
       const RasterSource* raster_source,
       const gfx::Rect& canvas_bitmap_rect,
       const gfx::Rect& canvas_playback_rect,
       float scale,
       const RasterSource::PlaybackSettings& playback_settings);
 
-  // Type-checking downcast routine.
-  virtual TileTaskRunner* AsTileTaskRunner() = 0;
+  // Tells the worker pool to shutdown after canceling all previously scheduled
+  // tasks. Reply callbacks are still guaranteed to run when
+  // CheckForCompletedTasks() is called.
+  virtual void Shutdown() = 0;
+
+  // Schedule running of tile tasks in |graph| and all dependencies.
+  // Previously scheduled tasks that are not in |graph| will be canceled unless
+  // already running. Once scheduled, reply callbacks are guaranteed to run for
+  // all tasks even if they later get canceled by another call to
+  // ScheduleTasks().
+  virtual void ScheduleTasks(TaskGraph* graph) = 0;
+
+  // Check for completed tasks and dispatch reply callbacks.
+  virtual void CheckForCompletedTasks() = 0;
+
+  // Returns the format to use for the tiles.
+  virtual ResourceFormat GetResourceFormat(bool must_support_alpha) const = 0;
+
+  // Determine if the resource requires swizzling.
+  virtual bool GetResourceRequiresSwizzle(bool must_support_alpha) const = 0;
+
+  // Downcasting routine for RasterBufferProvider interface.
+  virtual RasterBufferProvider* AsRasterBufferProvider() = 0;
+
+ protected:
+  // Check if resource format matches output format.
+  static bool ResourceFormatRequiresSwizzle(ResourceFormat format);
 };
 
 }  // namespace cc
 
 #endif  // CC_RASTER_TILE_TASK_WORKER_POOL_H_