Build Census as a grpc plugin
diff --git a/build.yaml b/build.yaml
index de4deeb..0bd138e 100644
--- a/build.yaml
+++ b/build.yaml
@@ -13,16 +13,24 @@
   public_headers:
   - include/grpc/census.h
   headers:
-  - src/core/lib/census/aggregation.h
-  - src/core/lib/census/mlog.h
-  - src/core/lib/census/rpc_metric_id.h
+  - src/core/ext/census/aggregation.h
+  - src/core/ext/census/census_interface.h
+  - src/core/ext/census/census_rpc_stats.h
+  - src/core/ext/census/grpc_filter.h
+  - src/core/ext/census/grpc_plugin.h
+  - src/core/ext/census/mlog.h
+  - src/core/ext/census/rpc_metric_id.h
   src:
-  - src/core/lib/census/context.c
-  - src/core/lib/census/initialize.c
-  - src/core/lib/census/mlog.c
-  - src/core/lib/census/operation.c
-  - src/core/lib/census/placeholders.c
-  - src/core/lib/census/tracing.c
+  - src/core/ext/census/context.c
+  - src/core/ext/census/grpc_context.c
+  - src/core/ext/census/grpc_filter.c
+  - src/core/ext/census/grpc_plugin.c
+  - src/core/ext/census/initialize.c
+  - src/core/ext/census/mlog.c
+  - src/core/ext/census/operation.c
+  - src/core/ext/census/placeholders.c
+  - src/core/ext/census/tracing.c
+  plugin: census_grpc_plugin
 - name: gpr
   public_headers:
   - include/grpc/support/alloc.h
@@ -248,8 +256,6 @@
   - include/grpc/status.h
   headers:
   - src/core/ext/lb_policy/grpclb/proto/grpc/lb/v0/load_balancer.pb.h
-  - src/core/lib/census/grpc_filter.h
-  - src/core/lib/census/grpc_plugin.h
   - src/core/lib/channel/channel_args.h
   - src/core/lib/channel/channel_stack.h
   - src/core/lib/channel/channel_stack_builder.h
@@ -322,8 +328,6 @@
   - src/core/lib/json/json_common.h
   - src/core/lib/json/json_reader.h
   - src/core/lib/json/json_writer.h
-  - src/core/lib/statistics/census_interface.h
-  - src/core/lib/statistics/census_rpc_stats.h
   - src/core/lib/surface/api_trace.h
   - src/core/lib/surface/call.h
   - src/core/lib/surface/call_test_only.h
@@ -345,9 +349,6 @@
   - src/core/lib/transport/transport_impl.h
   src:
   - src/core/ext/lb_policy/grpclb/proto/grpc/lb/v0/load_balancer.pb.c
-  - src/core/lib/census/grpc_context.c
-  - src/core/lib/census/grpc_filter.c
-  - src/core/lib/census/grpc_plugin.c
   - src/core/lib/channel/channel_args.c
   - src/core/lib/channel/channel_stack.c
   - src/core/lib/channel/channel_stack_builder.c