cc: Start using raster/eviction iterators in tile manager

cc/resources/picture_layer_tiling.h

Index: cc/resources/picture_layer_tiling.h
diff --git a/cc/resources/picture_layer_tiling.h b/cc/resources/picture_layer_tiling.h
index 92c28797a6ed59998517faa6f904a7d5f1a1757a..9c97c4125588940b9a7d76e78f4fe7de32703abd 100644
--- a/cc/resources/picture_layer_tiling.h
+++ b/cc/resources/picture_layer_tiling.h
@@ -59,6 +59,8 @@ class CC_EXPORT PictureLayerTiling {
 
     TilingRasterTileIterator& operator++();
 
+    bool HasTilesRequiredForActivation() const;

[reveman, 2014/04/24 00:17:34]

hm, this returns some state that depend on the position of the iterator and all
following elements. I think it's a bad idea to have such a function on an
iterator. If we can't land some change prior to this that moves the decision
whether we can activate to tile initialization completion time, could we instead
add a TilesRequiredForActivationAndNeedRasterCount() function to the
PictureLayerTiling class and use that in the tile manager instead?

[vmpstr, 2014/04/28 18:50:37]

Moved this to a separate patch.

+
     gfx::Rect TileBounds() const {
       DCHECK(*this);
       if (type_ == TilePriority::NOW) {