Merge branch 'direct-calls' into buffer_pools_for_realsies

Makefile

build.yaml

composer.json

doc/core/pending_api_cleanups.md

doc/cpp/pending_api_cleanups.md

etc/roots.pem

examples/node/static_codegen/greeter_client.js

examples/php/composer.json

include/grpc++/impl/codegen/client_context.h

include/grpc/impl/codegen/grpc_types.h

src/core/ext/client_config/client_channel.c

src/core/ext/client_config/lb_policy.h

src/core/ext/lb_policy/grpclb/grpclb.c

src/core/ext/resolver/dns/native/dns_resolver.c

src/core/ext/resolver/sockaddr/sockaddr_resolver.c

src/core/ext/transport/cronet/transport/cronet_transport.c

src/core/lib/channel/message_size_filter.c

src/core/lib/iomgr/error.h

src/core/lib/iomgr/udp_server.c

src/core/lib/surface/byte_buffer.c