Add a new finch experiment to control the system buffer size.

content/browser/renderer_host/p2p/socket_host_udp_unittest.cc

Index: content/browser/renderer_host/p2p/socket_host_udp_unittest.cc
diff --git a/content/browser/renderer_host/p2p/socket_host_udp_unittest.cc b/content/browser/renderer_host/p2p/socket_host_udp_unittest.cc
index 5d67a24fc3327563c21773cc973ae8ba7084e7b0..bcde983836fa3f654786b1c1aa33b90719877be5 100644
--- a/content/browser/renderer_host/p2p/socket_host_udp_unittest.cc
+++ b/content/browser/renderer_host/p2p/socket_host_udp_unittest.cc
@@ -373,4 +373,40 @@ TEST_F(P2PSocketHostUdpTest, ThrottleAfterLimitAfterReceive) {
   ASSERT_EQ(sent_packets_.size(), 4U);
 }
 
+TEST_F(P2PSocketHostUdpTest, PackUnpackCallRecord) {
+  uint64 packet_id_result;
+  uint64 ticks_diff;
+  uint64 random_prefix = 0xabcd1234uLL << 32;
+  ASSERT_EQ(random_prefix & ((1uLL << 32) - 1), 0uL);
+
+  uint64 packet_id = 12;
+  uint64 ticks_now = 12345;
+  uint64 call_record =
+      P2PSocketHostUdp::PackCallRecord(random_prefix + packet_id, ticks_now);
+  EXPECT_EQ(call_record, (ticks_now << 32) + packet_id);
+
+  // Increment the tick by 2.
+  P2PSocketHostUdp::UnpackCallRecord(call_record,
+                                     random_prefix,
+                                     ticks_now + 2,
+                                     &packet_id_result,
+                                     &ticks_diff);
+  EXPECT_EQ(packet_id_result, random_prefix + packet_id);
+  EXPECT_EQ(ticks_diff, 2uL);
+
+  // Try a large packet id and the tick is rounding over 2^32.
+  packet_id = 0xffffffff;
+  ticks_now = 0xffffff00;
+  call_record =
+      P2PSocketHostUdp::PackCallRecord(random_prefix + packet_id, ticks_now);
+  EXPECT_EQ(call_record, (ticks_now << 32) + 0xffffffff);
+  P2PSocketHostUdp::UnpackCallRecord(call_record,
+                                     random_prefix,
+                                     ticks_now + 0x150,
+                                     &packet_id_result,
+                                     &ticks_diff);
+  EXPECT_EQ(packet_id_result, random_prefix + packet_id);
+  EXPECT_EQ(ticks_diff, 0x150uL);
+}
+
 }  // namespace content