Implement service-side surface synchronization

cc/surfaces/surface_id_allocator.cc

Index: cc/surfaces/surface_id_allocator.cc
diff --git a/cc/surfaces/surface_id_allocator.cc b/cc/surfaces/surface_id_allocator.cc
index 84523e130561818b6a4e4cf5574d63e00fbecb3b..8c78e83422877b8d660741288835448d1654b772 100644
--- a/cc/surfaces/surface_id_allocator.cc
+++ b/cc/surfaces/surface_id_allocator.cc
@@ -16,10 +16,10 @@ SurfaceIdAllocator::SurfaceIdAllocator() : next_id_(1u) {}
 SurfaceIdAllocator::~SurfaceIdAllocator() {
 }
 
-LocalSurfaceId SurfaceIdAllocator::GenerateId() {
-  LocalSurfaceId id(next_id_, base::UnguessableToken::Create());
-  next_id_++;
-  return id;
+const LocalSurfaceId& SurfaceIdAllocator::GenerateId() {

[vmpstr, 2017/02/07 22:46:20]

Why this change?

[Fady Samuel, 2017/02/08 00:52:50]

It's not necessary for now. I've reverted it.

+  current_local_surface_id_ =
+      LocalSurfaceId(next_id_++, base::UnguessableToken::Create());
+  return current_local_surface_id_;
 }
 
 }  // namespace cc