Merge remote-tracking branch 'upstream/master' into service_config

README.md

doc/interop-test-descriptions.md

src/compiler/README.md

src/compiler/csharp_generator.cc

src/core/README.md

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/lb_policy/pick_first/pick_first.c

src/core/ext/lb_policy/round_robin/round_robin.c

...ext/transport/chttp2/server/secure/server_secure_chttp2.c

src/core/lib/iomgr/tcp_server.h

src/core/lib/iomgr/tcp_server_posix.c

src/core/lib/iomgr/tcp_server_windows.c

...ib/security/credentials/composite/composite_credentials.c

...ib/security/credentials/composite/composite_credentials.h

src/core/lib/security/credentials/credentials.c

src/core/lib/security/credentials/credentials.h

src/core/lib/security/credentials/fake/fake_credentials.c

src/core/lib/security/credentials/ssl/ssl_credentials.c