Merge github.com:grpc/grpc into varint_test

Makefile

build.yaml

examples/objective-c/auth_sample/Podfile

examples/objective-c/helloworld/Podfile

examples/objective-c/route_guide/Podfile

gRPC.podspec

include/grpc/support/port_platform.h

package.json

src/core/census/context.h

src/core/iomgr/endpoint_pair_posix.c

src/core/support/log.c

src/core/support/slice.c

src/core/surface/call.c

src/core/surface/call.h

src/core/surface/call_log_batch.c

src/core/transport/chttp2/frame_data.c

src/core/transport/chttp2/frame_data.h

src/core/transport/chttp2/hpack_encoder.c

src/core/transport/chttp2/hpack_parser.c

src/core/transport/chttp2/hpack_parser.h