There are times when we make changes that include a temporary shim for backward-compatibility (e.g., a macro or some other function to preserve the original API) to avoid having to bump the major version number in the next release. However, when we do eventually want to release a feature that does change the API in a non-backward-compatible way, we will wind up bumping the major version number anyway, at which point we can take the opportunity to clean up any pending backward-compatibility shims.

This file lists all pending backward-compatibility changes that should be cleaned up the next time we are going to bump the major version number:

remove GRPC_ARG_MAX_MESSAGE_LENGTH channel arg from include/grpc/impl/codegen/grpc_types.h (commit af00d8b) (cannot be done until after next grpc release, so that TensorFlow can use the same code both internally and externally)
require a C++ runtime for all languages wrapping core.
remove GRPC_ARG_HTTP2_MIN_SENT_PING_INTERVAL_WITHOUT_DATA_MS channel arg