tree c51b8c6324a38c36d002c7571612bea67af7f074
parent b4e0a834cd101417a5f2213459de332bc233573b
author Chia-I Wu <olv@google.com> 1536877078 -0700
committer Chia-I Wu <olv@google.com> 1537558837 -0700

surfaceflinger: simplify memory management for layerproto

Use std::vector<Layer> instead of a tree of std::unique_ptr<Layer>
to manage layers.  This significantly reduces the number of
allocations, and more importantly, we can get rid of "new" in
generateLayer.  Because there is no "new", it is easier to reason
that there is no leaked layer.

We still keep the pointers to top-level layers in
LayerTree::topLevelLayers.  But AFAICT, we probably don't need it
after all.

Test: dumpsys, winscope trace
Change-Id: I302c9115ab025b69e9ea05f4bcd759ed3ee4a8eb