Merge github.com:grpc/grpc into metadata_filter

BUILD

Makefile

Rakefile

build.yaml

build_config.rb

doc/images/load-balancing.png

doc/images/load-balancing.svg

doc/images/load_balancing_design.png

doc/load-balancing.md

doc/naming.md

doc/service_config.md

src/core/ext/census/tracing.c

...xt/transport/cronet/client/secure/cronet_channel_create.c

src/core/ext/transport/cronet/transport/cronet_api_dummy.c

src/core/ext/transport/cronet/transport/cronet_transport.c

src/objective-c/CronetFramework.podspec

src/objective-c/GRPCClient/GRPCCall+Cronet.h

src/objective-c/GRPCClient/GRPCCall+Cronet.m

src/objective-c/GRPCClient/private/GRPCChannel.m

...e-c/tests/CoreCronetEnd2EndTests/CoreCronetEnd2EndTests.m