Switch SurfaceId maps from base::hash_map to std::unordered_map.

cc/surfaces/surface_aggregator.cc

Index: cc/surfaces/surface_aggregator.cc
diff --git a/cc/surfaces/surface_aggregator.cc b/cc/surfaces/surface_aggregator.cc
index d60a2172b5dffe0e51b100b7b9c74b84dd3f054d..593f58967e8070cc2f91e4ef8a99657390353fc2 100644
--- a/cc/surfaces/surface_aggregator.cc
+++ b/cc/surfaces/surface_aggregator.cc
@@ -122,10 +122,11 @@ static void UnrefHelper(base::WeakPtr<SurfaceFactory> surface_factory,
 
 RenderPassId SurfaceAggregator::RemapPassId(RenderPassId surface_local_pass_id,
                                             SurfaceId surface_id) {
-  RenderPassIdAllocator* allocator = render_pass_allocator_map_.get(surface_id);
+  RenderPassIdAllocator* allocator =

[danakj, 2016/01/26 23:53:32]

You could write this code a bit shorter now I guess like

scoped_ptr<RenderPassIdAllocator>& allocator =
    render_pass_..._map_[surface_id];
if (!allocator)
  allocator.reset(new RenderPass....or(&nex.._id_);

Ie.. no need to set the thing into the map if you have a reference to it
already.

[lfg, 2016/01/27 00:53:14]

Done.

+      render_pass_allocator_map_[surface_id].get();
   if (!allocator) {
     allocator = new RenderPassIdAllocator(&next_render_pass_id_);
-    render_pass_allocator_map_.set(surface_id, make_scoped_ptr(allocator));
+    render_pass_allocator_map_[surface_id] = make_scoped_ptr(allocator);
   }
   allocator->AddKnownPass(surface_local_pass_id);
   return allocator->Remap(surface_local_pass_id);