net: Implement ChannelIDSourceChromium, which is based on Chromium's

net/quic/quic_crypto_server_stream_test.cc

Index: net/quic/quic_crypto_server_stream_test.cc
===================================================================
--- net/quic/quic_crypto_server_stream_test.cc	(revision 280648)
+++ net/quic/quic_crypto_server_stream_test.cc	(working copy)
@@ -67,8 +67,9 @@
     // We advance the clock initially because the default time is zero and the
     // strike register worries that we've just overflowed a uint32 time.
     connection_->AdvanceTime(QuicTime::Delta::FromSeconds(100000));
-    // TODO(rtenneti): Enable testing of ProofSource.
-    // crypto_config_.SetProofSource(CryptoTestUtils::ProofSourceForTesting());
+    // TODO(wtc): replace this with ProofSourceForTesting() when Chromium has
+    // a working ProofSourceForTesting().
+    crypto_config_.SetProofSource(CryptoTestUtils::FakeProofSourceForTesting());
     crypto_config_.set_strike_register_no_startup_period();
 
     CryptoTestUtils::SetupCryptoServerConfigForTest(