cc: Add more eviction categories to picture layer impl.

cc/resources/picture_layer_tiling.h

 // Copyright 2012 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_RESOURCES_PICTURE_LAYER_TILING_H_
 #define CC_RESOURCES_PICTURE_LAYER_TILING_H_
 
 #include <utility>
 #include <vector>
 
@@ skipping 39 matching lines @@
   virtual WhichTree GetTree() const = 0;
 
  protected:
   virtual ~PictureLayerTilingClient() {}
 };
 
 class CC_EXPORT PictureLayerTiling {
  public:
   enum EvictionCategory {
     EVENTUALLY,
+    EVENTUALLY_AND_REQUIRED_FOR_ACTIVATION,
     SOON,
+    SOON_AND_REQUIRED_FOR_ACTIVATION,
     NOW,
     NOW_AND_REQUIRED_FOR_ACTIVATION
   };
+  enum { NUM_EVICTION_CATEGORIES = NOW_AND_REQUIRED_FOR_ACTIVATION + 1 };

[vmpstr, 2014/08/14 06:23:48]

I'm not sure what our style guide says about enums anymore :) I prefer this
approach, but if you have another preference I'll be happy to change it.

[reveman, 2014/08/14 09:01:50]

We don't have a nice consistent mechanism for this. I was trying to create this
at one point (https://codereview.chromium.org/22911037/) but never had the time
to make it build on win and push for it as a standard in cc and/or chromium.

The problem with the approach you use here is that one might easily forget to
update NUM_EVICTION_CATEGORIES when adding more enum values.

enum EvictionCategory {
  EVENTUALLY,
  SOON,
  NOW,
  NOW_AND_REQUIRED_FOR_ACTIVATION,
  kEvictionCategoryMax = NOW_AND_REQUIRED_FOR_ACTIVATION
}

is a bit better imo but suffers from the same problem. Adding
NUM_EVICTION_CATEGORIES at the end is another option but the problem with that
is obvious.

I prefer if we avoid array indexing using enum values until we have a nice
mechanism to do this. How about we keep this as before but create a bug for
adding a proper mechanism for using enum values as array indexes and put a TODO
here? You can assign the bug to me and I'll try to finish up that old cl.

[danakj, 2014/08/14 16:55:26]

Security team (tsepez) has been adding a LAST_FOO_BAR to enums like

enum Value {
a
b
LAST_VALUE=b
};

so we should probly be consistent with that.

[vmpstr, 2014/08/14 22:05:50]

Removed this for now, added a TODO instead.

+
   class CC_EXPORT TilingRasterTileIterator {
    public:
     TilingRasterTileIterator();
     TilingRasterTileIterator(PictureLayerTiling* tiling, WhichTree tree);
     ~TilingRasterTileIterator();
 
     operator bool() const { return !!current_tile_; }
     const Tile* operator*() const { return current_tile_; }
     Tile* operator*() { return current_tile_; }
     TilePriority::PriorityBin get_type() const {
@@ skipping 255 matching lines @@
   gfx::Rect current_visible_rect_;
   gfx::Rect current_skewport_rect_;
   gfx::Rect current_soon_border_rect_;
   gfx::Rect current_eventually_rect_;
 
   bool has_visible_rect_tiles_;
   bool has_skewport_rect_tiles_;
   bool has_soon_border_rect_tiles_;
   bool has_eventually_rect_tiles_;
 
-  std::vector<Tile*> eventually_eviction_tiles_;
-  std::vector<Tile*> soon_eviction_tiles_;
-  std::vector<Tile*> now_eviction_tiles_;
-  std::vector<Tile*> now_and_required_for_activation_eviction_tiles_;
+  std::vector<Tile*> eviction_tiles_[NUM_EVICTION_CATEGORIES];
   bool eviction_tiles_cache_valid_;
   TreePriority eviction_cache_tree_priority_;
 
  private:
   DISALLOW_ASSIGN(PictureLayerTiling);
 
   RectExpansionCache expansion_cache_;
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_PICTURE_LAYER_TILING_H_