Merge pull request #3027 from jboeuf/security_connector_refactoring

BUILD

Makefile

build.yaml

gRPC.podspec

src/core/httpcli/httpcli_security_connector.c

src/core/security/handshake.c

src/core/security/handshake.h

src/core/security/security_connector.c

src/core/security/security_connector.h

src/core/security/server_secure_chttp2.c

src/core/surface/secure_channel_create.c

tools/doxygen/Doxyfile.core.internal

tools/run_tests/sources_and_headers.json

vsprojects/vcxproj/grpc/grpc.vcxproj

vsprojects/vcxproj/grpc/grpc.vcxproj.filters