cc: Implement geometry-based tile eviction

cc/resources/eviction_tile_priority_queue.cc

Index: cc/resources/eviction_tile_priority_queue.cc
diff --git a/cc/resources/eviction_tile_priority_queue.cc b/cc/resources/eviction_tile_priority_queue.cc
index 4d6698745897caaa320a0584b2e8a4bae120ccac..cd681ef1455c5413cc70ccec013ecbcd5bc7ba98 100644
--- a/cc/resources/eviction_tile_priority_queue.cc
+++ b/cc/resources/eviction_tile_priority_queue.cc
@@ -200,6 +200,8 @@ EvictionTilePriorityQueue::PairedTilingSetQueue::NextTileIteratorTree(
 
   const Tile* active_tile = active_queue->Top();
   const Tile* pending_tile = pending_queue->Top();
+
+  // If tiles are the same, it doesn't matter which tree we return.
   if (active_tile == pending_tile)
     return ACTIVE_TREE;
 
@@ -208,6 +210,15 @@ EvictionTilePriorityQueue::PairedTilingSetQueue::NextTileIteratorTree(
   const TilePriority& pending_priority =
       pending_tile->priority_for_tree_priority(tree_priority);
 
+  // If the bins are the same and activation differs, then return the tree of
+  // the tile not required for activation.
+  if (active_priority.priority_bin == pending_priority.priority_bin &&
+      active_tile->required_for_activation() !=
+          pending_tile->required_for_activation()) {
+    return active_tile->required_for_activation() ? PENDING_TREE : ACTIVE_TREE;
+  }
+
+  // Return tile with a lower priority.
   if (pending_priority.IsHigherPriorityThan(active_priority))
     return ACTIVE_TREE;
   return PENDING_TREE;