Improvements to uses of base::SmallMap

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 098b7bd3b452072165fecfa49ae49c03ab400fe3..4e952185be888f843249fd166b9f70011244b48e 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -1161,7 +1161,7 @@ void LayerTreeHostImpl::RemoveRenderPasses(FrameData* frame) {
   std::set<int> pass_exists;

[brettw, 2017/04/19 16:29:48]

We discussed in chat also changing this to a flat_set

   // A set of RenderPassDrawQuads that we have seen (stored by the RenderPasses
   // they refer to).
-  base::SmallMap<std::unordered_map<int, int>> pass_references;
+  base::small_map<std::unordered_map<int, int>> pass_references;

[danakj, 2017/04/18 21:35:50]

This should be a flat_map

 
   // Iterate RenderPasses in draw order, removing empty render passes (except
   // the root RenderPass).