Merge pull request #7611 from markdroth/http_connect

BUILD

CMakeLists.txt

Makefile

binding.gyp

build.yaml

config.m4

gRPC-Core.podspec

grpc.gemspec

package.xml

src/core/ext/client_config/client_channel.c

src/core/ext/client_config/http_connect_handshaker.c

src/core/ext/client_config/http_connect_handshaker.h

src/core/ext/client_config/lb_policy_factory.h

src/core/ext/client_config/resolver_result.c

src/core/ext/client_config/resolver_result.h

src/core/ext/client_config/subchannel.h

src/core/ext/client_config/subchannel_index.c

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