Test for all our CC algorithms under >1 network scenarios.

Test for all our CC algorithms under >1 network scenarios.

The purpose of this test suite is to exercise all our existing
congestion-control algorithms under a variety of network scenarios,
using our handy-dandy network simulator.

Right now, the tests are parameterized by congestion-control
algorithm.  Each test performs a simple transfers under a different
network condition, using the given CC algorithm.  It measures the
amount of time it takes to perform the transfer and prints out some
stats.  If the transfer does not complete within a reasonable amount
of time (where "reasonable" depends on the scenario), the test will
fail.

The tests may use additional pass/fail criteria, such as maximum
acceptable retransmissions, in the future.

I've included a few simple scenarios to get started.  I expect these
to expand as we discover new conditions to test.

Merge internal change: 140494757

R=rch@chromium.org
BUG=

[Ryan Hamilton, 2016-12-06 22:16:30]

lgtm