Reorganize ext tree

- filters live under filters
- lb_policy, resolver implementations (being part of client_channel) live under client_channel
diff --git a/gRPC-Core.podspec b/gRPC-Core.podspec
index d750a5b..e033164 100644
--- a/gRPC-Core.podspec
+++ b/gRPC-Core.podspec
@@ -410,37 +410,37 @@
                       'src/core/tsi/transport_security.h',
                       'src/core/tsi/transport_security_interface.h',
                       'src/core/ext/transport/chttp2/server/chttp2_server.h',
-                      'src/core/ext/client_channel/client_channel.h',
-                      'src/core/ext/client_channel/client_channel_factory.h',
-                      'src/core/ext/client_channel/connector.h',
-                      'src/core/ext/client_channel/http_connect_handshaker.h',
-                      'src/core/ext/client_channel/http_proxy.h',
-                      'src/core/ext/client_channel/lb_policy.h',
-                      'src/core/ext/client_channel/lb_policy_factory.h',
-                      'src/core/ext/client_channel/lb_policy_registry.h',
-                      'src/core/ext/client_channel/parse_address.h',
-                      'src/core/ext/client_channel/proxy_mapper.h',
-                      'src/core/ext/client_channel/proxy_mapper_registry.h',
-                      'src/core/ext/client_channel/resolver.h',
-                      'src/core/ext/client_channel/resolver_factory.h',
-                      'src/core/ext/client_channel/resolver_registry.h',
-                      'src/core/ext/client_channel/retry_throttle.h',
-                      'src/core/ext/client_channel/subchannel.h',
-                      'src/core/ext/client_channel/subchannel_index.h',
-                      'src/core/ext/client_channel/uri_parser.h',
+                      'src/core/ext/filters/client_channel/client_channel.h',
+                      'src/core/ext/filters/client_channel/client_channel_factory.h',
+                      'src/core/ext/filters/client_channel/connector.h',
+                      'src/core/ext/filters/client_channel/http_connect_handshaker.h',
+                      'src/core/ext/filters/client_channel/http_proxy.h',
+                      'src/core/ext/filters/client_channel/lb_policy.h',
+                      'src/core/ext/filters/client_channel/lb_policy_factory.h',
+                      'src/core/ext/filters/client_channel/lb_policy_registry.h',
+                      'src/core/ext/filters/client_channel/parse_address.h',
+                      'src/core/ext/filters/client_channel/proxy_mapper.h',
+                      'src/core/ext/filters/client_channel/proxy_mapper_registry.h',
+                      'src/core/ext/filters/client_channel/resolver.h',
+                      'src/core/ext/filters/client_channel/resolver_factory.h',
+                      'src/core/ext/filters/client_channel/resolver_registry.h',
+                      'src/core/ext/filters/client_channel/retry_throttle.h',
+                      'src/core/ext/filters/client_channel/subchannel.h',
+                      'src/core/ext/filters/client_channel/subchannel_index.h',
+                      'src/core/ext/filters/client_channel/uri_parser.h',
                       'src/core/ext/transport/chttp2/client/chttp2_connector.h',
-                      'src/core/ext/lb_policy/grpclb/grpclb.h',
-                      'src/core/ext/lb_policy/grpclb/grpclb_channel.h',
-                      'src/core/ext/lb_policy/grpclb/load_balancer_api.h',
-                      'src/core/ext/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h',
+                      'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.h',
+                      'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.h',
+                      'src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.h',
+                      'src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h',
                       'third_party/nanopb/pb.h',
                       'third_party/nanopb/pb_common.h',
                       'third_party/nanopb/pb_decode.h',
                       'third_party/nanopb/pb_encode.h',
-                      'src/core/ext/resolver/dns/c_ares/grpc_ares_ev_driver.h',
-                      'src/core/ext/resolver/dns/c_ares/grpc_ares_wrapper.h',
-                      'src/core/ext/load_reporting/load_reporting.h',
-                      'src/core/ext/load_reporting/load_reporting_filter.h',
+                      'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.h',
+                      'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h',
+                      'src/core/ext/filters/load_reporting/load_reporting.h',
+                      'src/core/ext/filters/load_reporting/load_reporting_filter.h',
                       'src/core/ext/census/aggregation.h',
                       'src/core/ext/census/base_resources.h',
                       'src/core/ext/census/census_interface.h',
@@ -634,47 +634,47 @@
                       'src/core/tsi/transport_security.c',
                       'src/core/ext/transport/chttp2/server/chttp2_server.c',
                       'src/core/ext/transport/chttp2/client/secure/secure_channel_create.c',
-                      'src/core/ext/client_channel/channel_connectivity.c',
-                      'src/core/ext/client_channel/client_channel.c',
-                      'src/core/ext/client_channel/client_channel_factory.c',
-                      'src/core/ext/client_channel/client_channel_plugin.c',
-                      'src/core/ext/client_channel/connector.c',
-                      'src/core/ext/client_channel/http_connect_handshaker.c',
-                      'src/core/ext/client_channel/http_proxy.c',
-                      'src/core/ext/client_channel/lb_policy.c',
-                      'src/core/ext/client_channel/lb_policy_factory.c',
-                      'src/core/ext/client_channel/lb_policy_registry.c',
-                      'src/core/ext/client_channel/parse_address.c',
-                      'src/core/ext/client_channel/proxy_mapper.c',
-                      'src/core/ext/client_channel/proxy_mapper_registry.c',
-                      'src/core/ext/client_channel/resolver.c',
-                      'src/core/ext/client_channel/resolver_factory.c',
-                      'src/core/ext/client_channel/resolver_registry.c',
-                      'src/core/ext/client_channel/retry_throttle.c',
-                      'src/core/ext/client_channel/subchannel.c',
-                      'src/core/ext/client_channel/subchannel_index.c',
-                      'src/core/ext/client_channel/uri_parser.c',
+                      'src/core/ext/filters/client_channel/channel_connectivity.c',
+                      'src/core/ext/filters/client_channel/client_channel.c',
+                      'src/core/ext/filters/client_channel/client_channel_factory.c',
+                      'src/core/ext/filters/client_channel/client_channel_plugin.c',
+                      'src/core/ext/filters/client_channel/connector.c',
+                      'src/core/ext/filters/client_channel/http_connect_handshaker.c',
+                      'src/core/ext/filters/client_channel/http_proxy.c',
+                      'src/core/ext/filters/client_channel/lb_policy.c',
+                      'src/core/ext/filters/client_channel/lb_policy_factory.c',
+                      'src/core/ext/filters/client_channel/lb_policy_registry.c',
+                      'src/core/ext/filters/client_channel/parse_address.c',
+                      'src/core/ext/filters/client_channel/proxy_mapper.c',
+                      'src/core/ext/filters/client_channel/proxy_mapper_registry.c',
+                      'src/core/ext/filters/client_channel/resolver.c',
+                      'src/core/ext/filters/client_channel/resolver_factory.c',
+                      'src/core/ext/filters/client_channel/resolver_registry.c',
+                      'src/core/ext/filters/client_channel/retry_throttle.c',
+                      'src/core/ext/filters/client_channel/subchannel.c',
+                      'src/core/ext/filters/client_channel/subchannel_index.c',
+                      'src/core/ext/filters/client_channel/uri_parser.c',
                       'src/core/ext/transport/chttp2/client/chttp2_connector.c',
                       'src/core/ext/transport/chttp2/server/insecure/server_chttp2.c',
                       'src/core/ext/transport/chttp2/server/insecure/server_chttp2_posix.c',
                       'src/core/ext/transport/chttp2/client/insecure/channel_create.c',
                       'src/core/ext/transport/chttp2/client/insecure/channel_create_posix.c',
-                      'src/core/ext/lb_policy/grpclb/grpclb.c',
-                      'src/core/ext/lb_policy/grpclb/grpclb_channel_secure.c',
-                      'src/core/ext/lb_policy/grpclb/load_balancer_api.c',
-                      'src/core/ext/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.c',
+                      'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.c',
+                      'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel_secure.c',
+                      'src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.c',
+                      'src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.c',
                       'third_party/nanopb/pb_common.c',
                       'third_party/nanopb/pb_decode.c',
                       'third_party/nanopb/pb_encode.c',
-                      'src/core/ext/lb_policy/pick_first/pick_first.c',
-                      'src/core/ext/lb_policy/round_robin/round_robin.c',
-                      'src/core/ext/resolver/dns/c_ares/dns_resolver_ares.c',
-                      'src/core/ext/resolver/dns/c_ares/grpc_ares_ev_driver_posix.c',
-                      'src/core/ext/resolver/dns/c_ares/grpc_ares_wrapper.c',
-                      'src/core/ext/resolver/dns/native/dns_resolver.c',
-                      'src/core/ext/resolver/sockaddr/sockaddr_resolver.c',
-                      'src/core/ext/load_reporting/load_reporting.c',
-                      'src/core/ext/load_reporting/load_reporting_filter.c',
+                      'src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.c',
+                      'src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.c',
+                      'src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.c',
+                      'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.c',
+                      'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.c',
+                      'src/core/ext/filters/client_channel/resolver/dns/native/dns_resolver.c',
+                      'src/core/ext/filters/client_channel/resolver/sockaddr/sockaddr_resolver.c',
+                      'src/core/ext/filters/load_reporting/load_reporting.c',
+                      'src/core/ext/filters/load_reporting/load_reporting_filter.c',
                       'src/core/ext/census/base_resources.c',
                       'src/core/ext/census/context.c',
                       'src/core/ext/census/gen/census.pb.c',
@@ -860,37 +860,37 @@
                               'src/core/tsi/transport_security.h',
                               'src/core/tsi/transport_security_interface.h',
                               'src/core/ext/transport/chttp2/server/chttp2_server.h',
-                              'src/core/ext/client_channel/client_channel.h',
-                              'src/core/ext/client_channel/client_channel_factory.h',
-                              'src/core/ext/client_channel/connector.h',
-                              'src/core/ext/client_channel/http_connect_handshaker.h',
-                              'src/core/ext/client_channel/http_proxy.h',
-                              'src/core/ext/client_channel/lb_policy.h',
-                              'src/core/ext/client_channel/lb_policy_factory.h',
-                              'src/core/ext/client_channel/lb_policy_registry.h',
-                              'src/core/ext/client_channel/parse_address.h',
-                              'src/core/ext/client_channel/proxy_mapper.h',
-                              'src/core/ext/client_channel/proxy_mapper_registry.h',
-                              'src/core/ext/client_channel/resolver.h',
-                              'src/core/ext/client_channel/resolver_factory.h',
-                              'src/core/ext/client_channel/resolver_registry.h',
-                              'src/core/ext/client_channel/retry_throttle.h',
-                              'src/core/ext/client_channel/subchannel.h',
-                              'src/core/ext/client_channel/subchannel_index.h',
-                              'src/core/ext/client_channel/uri_parser.h',
+                              'src/core/ext/filters/client_channel/client_channel.h',
+                              'src/core/ext/filters/client_channel/client_channel_factory.h',
+                              'src/core/ext/filters/client_channel/connector.h',
+                              'src/core/ext/filters/client_channel/http_connect_handshaker.h',
+                              'src/core/ext/filters/client_channel/http_proxy.h',
+                              'src/core/ext/filters/client_channel/lb_policy.h',
+                              'src/core/ext/filters/client_channel/lb_policy_factory.h',
+                              'src/core/ext/filters/client_channel/lb_policy_registry.h',
+                              'src/core/ext/filters/client_channel/parse_address.h',
+                              'src/core/ext/filters/client_channel/proxy_mapper.h',
+                              'src/core/ext/filters/client_channel/proxy_mapper_registry.h',
+                              'src/core/ext/filters/client_channel/resolver.h',
+                              'src/core/ext/filters/client_channel/resolver_factory.h',
+                              'src/core/ext/filters/client_channel/resolver_registry.h',
+                              'src/core/ext/filters/client_channel/retry_throttle.h',
+                              'src/core/ext/filters/client_channel/subchannel.h',
+                              'src/core/ext/filters/client_channel/subchannel_index.h',
+                              'src/core/ext/filters/client_channel/uri_parser.h',
                               'src/core/ext/transport/chttp2/client/chttp2_connector.h',
-                              'src/core/ext/lb_policy/grpclb/grpclb.h',
-                              'src/core/ext/lb_policy/grpclb/grpclb_channel.h',
-                              'src/core/ext/lb_policy/grpclb/load_balancer_api.h',
-                              'src/core/ext/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h',
+                              'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.h',
+                              'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.h',
+                              'src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.h',
+                              'src/core/ext/filters/client_channel/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h',
                               'third_party/nanopb/pb.h',
                               'third_party/nanopb/pb_common.h',
                               'third_party/nanopb/pb_decode.h',
                               'third_party/nanopb/pb_encode.h',
-                              'src/core/ext/resolver/dns/c_ares/grpc_ares_ev_driver.h',
-                              'src/core/ext/resolver/dns/c_ares/grpc_ares_wrapper.h',
-                              'src/core/ext/load_reporting/load_reporting.h',
-                              'src/core/ext/load_reporting/load_reporting_filter.h',
+                              'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.h',
+                              'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h',
+                              'src/core/ext/filters/load_reporting/load_reporting.h',
+                              'src/core/ext/filters/load_reporting/load_reporting_filter.h',
                               'src/core/ext/census/aggregation.h',
                               'src/core/ext/census/base_resources.h',
                               'src/core/ext/census/census_interface.h',