Merge github.com:grpc/grpc into bm_closure

src/core/ext/transport/chttp2/transport/chttp2_transport.c

src/core/ext/transport/chttp2/transport/internal.h

src/core/ext/transport/chttp2/transport/parsing.c

src/core/ext/transport/chttp2/transport/writing.c

src/core/lib/channel/http_server_filter.c

src/core/lib/iomgr/ev_epoll_linux.c

src/core/lib/iomgr/ev_poll_posix.c

src/core/lib/iomgr/ev_posix.c

src/core/lib/iomgr/ev_posix.h

src/core/lib/iomgr/pollset.h

src/core/lib/iomgr/pollset_uv.c

src/core/lib/iomgr/pollset_windows.c

src/core/lib/surface/channel.c

src/core/lib/surface/completion_queue.c

src/core/lib/surface/completion_queue.h

src/core/lib/surface/init.c

src/python/grpcio/grpc/_channel.py

test/core/internal_api_canaries/iomgr.c

test/cpp/microbenchmarks/bm_fullstack.cc

tools/internal_ci/linux/grpc_interop.cfg