Allow specifying DNS server to query for c-ares via URI authority.

Add trace protector to flag

Set Frame Size to Bytes per Microsecond

Fix minor problems in server backward compatibility

Make cq_verifier output more readable

Fix some races in tests

Add MacOS interop and UBSan C to internal CI

Add unary fullstack trickle to bm json

Blanket suppress protobuf from ubsan runs

C++ compatibility fixes

Implement grpclb drop support.

Upmerge v1.3.x branch to master

C#: Dont use non-blittable types in native method signatures

Fix runtests --force_default_poller on linux

Unref pending events under cq lock

Doxygen cpp nits

PHP: fix pecl extension version

PHP: fix pecl extension after cc files are added

Add Backward compatibility API to C++

Fixes to subchannel and its index

Fix hpack_size test

PHP: stop requiring google/protobuf PHP implementation