Merge branch 'master' of https://github.com/grpc/grpc into slice_to_cstring

BUILD

Makefile

build.json

src/core/iomgr/fd_posix.c

src/core/security/security_connector.c

src/core/security/security_context.c

src/core/security/security_context.h

src/core/security/server_auth_filter.c

src/core/transport/chttp2/incoming_metadata.c

src/core/transport/chttp2_transport.c

src/core/transport/metadata.c

src/core/transport/transport.c

src/core/transport/transport.h

src/core/transport/transport_op_string.c

src/objective-c/ProtoRPC/ProtoRPC.m

src/python/src/grpc/_adapter/_c/types.h

src/python/src/grpc/_adapter/_c/utility.c

src/python/src/grpc/_adapter/_intermediary_low.py

src/python/src/grpc/_adapter/_intermediary_low_test.py

templates/BUILD.template