Populate latency field in final_info.

Makefile

src/core/ext/client_channel/client_channel.c

src/core/ext/client_channel/subchannel.c

src/core/ext/client_channel/subchannel.h

src/core/lib/channel/channel_stack.c

src/core/lib/channel/channel_stack.h

src/core/lib/surface/call.c

test/core/channel/channel_stack_test.c

test/core/end2end/end2end_nosec_tests.c

test/core/end2end/end2end_tests.c

test/core/end2end/gen_build_yaml.py

test/core/end2end/tests/filter_latency.c

tools/run_tests/sources_and_headers.json

tools/run_tests/tests.json

...end/tests/end2end_nosec_tests/end2end_nosec_tests.vcxproj

...s/end2end_nosec_tests/end2end_nosec_tests.vcxproj.filters

...oj/test/end2end/tests/end2end_tests/end2end_tests.vcxproj

...end2end/tests/end2end_tests/end2end_tests.vcxproj.filters