cc: Add checker-imaging support to TileManager.

cc/playback/raster_source.h

 // Copyright 2014 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_PLAYBACK_RASTER_SOURCE_H_
 #define CC_PLAYBACK_RASTER_SOURCE_H_
 
 #include <stddef.h>
 
 #include <memory>
@@ skipping 13 matching lines @@
 
 namespace cc {
 class DisplayItemList;
 class DrawImage;
 class ImageDecodeCache;
 
 class CC_EXPORT RasterSource : public base::RefCountedThreadSafe<RasterSource> {
  public:
   struct CC_EXPORT PlaybackSettings {
     PlaybackSettings();
+    PlaybackSettings(const PlaybackSettings&);
+    ~PlaybackSettings();
 
     // If set to true, this indicates that the canvas has already been
     // rasterized into. This means that the canvas cannot be cleared safely.
     bool playback_to_shared_canvas;
 
     // If set to true, none of the images will be rasterized.
     bool skip_images;
 
     // If set to true, we will use an image hijack canvas, which enables
     // compositor image caching.
     bool use_image_hijack_canvas;
+
+    // If non-empty, an image hijack canvas will be used to skip these images
+    // during raster.
+    std::unordered_set<ImageId> images_to_skip;

[vmpstr, 2017/02/03 23:42:32]

Hmm this feels like a wrong place to put this. How different would this patch
look if we pass image_to_skip as a separate argument to the functions that need
it?

In other words, I want to avoid having PlaybackSettings as a general grab bag of
parameters we want to plumb. This is the reason why for example rect/scale are
passed separately.

What do you think?

[Khushal, 2017/02/07 00:25:32]

It will be a lot of plumbing. The set has to finally reach the ImageHijackCanvas
in RasterSource::PlaybackToCanvas. And it starts from RasterTaskImpl. So
RasterTaskImpl->RasterBuffer->RasterBufferProvider->RasterSource::PlaybackToCanvas->RasterSource::PlaybackToCanvas
(which finally creates the ImageHijackCanvas. The plumbing is fine, but I don't
see much advantage from it. In general every setting that concerns with how we
deal with images during raster is here so it felt better to keep that
consolidated in one place.

   };
 
   static scoped_refptr<RasterSource> CreateFromRecordingSource(
       const RecordingSource* other,
       bool can_use_lcd_text);
 
   // TODO(trchen): Deprecated.
   void PlaybackToCanvas(SkCanvas* canvas,
                         const gfx::Rect& canvas_bitmap_rect,
                         const gfx::Rect& canvas_playback_rect,
@@ skipping 102 matching lines @@
   void RasterCommon(SkCanvas* canvas, SkPicture::AbortCallback* callback) const;
 
   void PrepareForPlaybackToCanvas(SkCanvas* canvas) const;
 
   DISALLOW_COPY_AND_ASSIGN(RasterSource);
 };
 
 }  // namespace cc
 
 #endif  // CC_PLAYBACK_RASTER_SOURCE_H_