Resolved merge conflicts

CONTRIBUTING.md

Makefile

build.json

etc/roots.pem

examples/pubsub/pubsub.proto

include/grpc/grpc_security.h

include/grpc/support/host_port.h

src/compiler/python_plugin.cc

src/compiler/ruby_generator_map-inl.h

src/core/channel/channel_stack.h

src/core/debug/trace.c

src/core/debug/trace.h

src/core/httpcli/httpcli.c

src/core/iomgr/fd_posix.c

src/core/iomgr/fd_posix.h

src/core/iomgr/pollset_multipoller_with_poll_posix.c

src/core/iomgr/pollset_posix.c

src/core/iomgr/resolve_address_posix.c

src/core/iomgr/resolve_address_windows.c

src/core/iomgr/tcp_client_posix.c