Expose the list of remapped channels from LogReader

This helps us track more reliably which channels are remapped and which
aren't for any applications which automatically find channels.

Change-Id: Iae344bc613f53e15afac7a33d5c766defcb09ee6
Signed-off-by: Austin Schuh <austin.schuh@bluerivertech.com>
diff --git a/aos/events/logging/logger_test.cc b/aos/events/logging/logger_test.cc
index 8d8a2a6..77333d6 100644
--- a/aos/events/logging/logger_test.cc
+++ b/aos/events/logging/logger_test.cc
@@ -1774,6 +1774,11 @@
   SimulatedEventLoopFactory log_reader_factory(reader.configuration());
   log_reader_factory.set_send_delay(chrono::microseconds(0));
 
+  std::vector<const Channel *> remapped_channels = reader.RemappedChannels();
+  ASSERT_EQ(remapped_channels.size(), 1u);
+  EXPECT_EQ(remapped_channels[0]->name()->string_view(), "/original/pi1/aos");
+  EXPECT_EQ(remapped_channels[0]->type()->string_view(), "aos.timing.Report");
+
   reader.Register(&log_reader_factory);
 
   const Node *pi1 =