cc: Rename ImageDecodeController to ImageDecodeCache.

cc/tiles/image_decode_controller.h

-// Copyright 2015 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_TILES_IMAGE_DECODE_CONTROLLER_H_
-#define CC_TILES_IMAGE_DECODE_CONTROLLER_H_
-
-#include "base/memory/ref_counted.h"
-#include "cc/playback/decoded_draw_image.h"
-#include "cc/playback/draw_image.h"
-#include "cc/tiles/tile_priority.h"
-
-namespace cc {
-
-class TileTask;
-
-// ImageDecodeController is responsible for generating decode tasks, decoding
-// images, storing images in cache, and being able to return the decoded images
-// when requested.
-
-// ImageDecodeController is responsible for the following things:
-// 1. Given a DrawImage, it can return an TileTask which when run will
-//    decode and cache the resulting image. If the image does not need a task to
-//    be decoded, then nullptr will be returned. The return value of the
-//    function indicates whether the image was or is going to be locked, so an
-//    unlock will be required.
-// 2. Given a cache key and a DrawImage, it can decode the image and store it in
-//    the cache. Note that it is important that this function is only accessed
-//    via an image decode task.
-// 3. Given a DrawImage, it can return a DecodedDrawImage, which represented the
-//    decoded version of the image. Note that if the image is not in the cache
-//    and it needs to be scaled/decoded, then this decode will happen as part of
-//    getting the image. As such, this should only be accessed from a raster
-//    thread.
-class CC_EXPORT ImageDecodeController {
- public:
-  // This information should be used strictly in tracing, UMA, and any other
-  // reporting systems.
-  struct TracingInfo {
-    TracingInfo(uint64_t prepare_tiles_id,
-                TilePriority::PriorityBin requesting_tile_bin)
-        : prepare_tiles_id(prepare_tiles_id),
-          requesting_tile_bin(requesting_tile_bin) {}
-    TracingInfo() : TracingInfo(0, TilePriority::NOW) {}
-
-    // ID for the current prepare tiles call.
-    const uint64_t prepare_tiles_id;
-
-    // The bin of the tile that caused this image to be requested.
-    const TilePriority::PriorityBin requesting_tile_bin;
-  };
-
-  virtual ~ImageDecodeController() {}
-
-  // Fill in an TileTask which will decode the given image when run. In
-  // case the image is already cached, fills in nullptr. Returns true if the
-  // image needs to be unreffed when the caller is finished with it.
-  //
-  // This is called by the tile manager (on the compositor thread) when creating
-  // a raster task.
-  virtual bool GetTaskForImageAndRef(const DrawImage& image,
-                                     const TracingInfo& tracing_info,
-                                     scoped_refptr<TileTask>* task) = 0;
-  // Unrefs an image. When the tile is finished, this should be called for every
-  // GetTaskForImageAndRef call that returned true.
-  virtual void UnrefImage(const DrawImage& image) = 0;
-
-  // Returns a decoded draw image. This may cause a decode if the image was not
-  // predecoded.
-  //
-  // This is called by a raster task (on a worker thread) when an image is
-  // required.
-  virtual DecodedDrawImage GetDecodedImageForDraw(const DrawImage& image) = 0;
-  // Unrefs an image. This should be called for every GetDecodedImageForDraw
-  // when the draw with the image is finished.
-  virtual void DrawWithImageFinished(const DrawImage& image,
-                                     const DecodedDrawImage& decoded_image) = 0;
-
-  // This function informs the controller that now is a good time to clean up
-  // memory. This is called periodically from the compositor thread.
-  virtual void ReduceCacheUsage() = 0;
-
-  // This function informs the controller that we are hidden and should not be
-  // retaining cached resources longer than needed.
-  virtual void SetShouldAggressivelyFreeResources(
-      bool aggressively_free_resources) = 0;
-};
-
-}  // namespace cc
-
-#endif  // CC_TILES_IMAGE_DECODE_CONTROLLER_H_