cc: Report only on active tiles in tracing.

cc/trees/layer_tree_host_impl.cc

Index: cc/trees/layer_tree_host_impl.cc
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index f04a96cc1ee008b738d9d06839497a317f7ea1fc..82ae700ea9abeb29dd6d3e7996bd252c1b1cfe68 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -3219,9 +3219,15 @@ void LayerTreeHostImpl::AsValueWithFrameInto(
   state->BeginDictionary("device_viewport_size");
   MathUtil::AddToTracedValue(device_viewport_size_, state);
   state->EndDictionary();
+
+  std::set<const Tile*> tiles;
+  active_tree_->AllTilesForTracingInto(&tiles);
+  if (pending_tree_)
+    pending_tree_->AllTilesForTracingInto(&tiles);
+
   if (tile_manager_) {
     state->BeginArray("tiles");
-    tile_manager_->AllTilesAsValueInto(state);
+    tile_manager_->AllTilesAsValueInto(state, tiles);

[enne (OOO), 2014/08/20 17:37:34]

Something seems redundant here.  Why do you need to get tiles from both the
trees as well as the tile manager? It seems like you'd want either or?  Am I
misunderstanding what lives in TileManager's tile map these days?

[vmpstr, 2014/08/20 17:41:11]

TileManager's tiles include recycled tiles (in fact, those are literally all the
tiles that have been created). Active/pending tree tiles are the ones that are
"in play" this frame. An alternative would be to plumb some sort of a
"IsTileOnActiveOrPendingTree" to tile manager via client which would search for
the tile in the trees, but this seems a more direct-ish approach.

[enne (OOO), 2014/08/20 18:05:42]

Should the TileManager::AllTilesAsValueInto get removed, then?

[vmpstr, 2014/08/20 18:18:58]

Hmm. Well, I don't really know. I feel like it's a good thing to log all the
tiles, even the recycle ones? I don't really have a justification for that
though. Nat, do you think these recycle tiles will ever be useful in trace
viewer? If not, I'll just remove the tile manager tile dump

     state->EndArray();
 
     state->BeginDictionary("tile_manager_basic_state");