Add library function to lookup storage duration per channel

This sets us up to actually add configuration per channel and have all
the call sites automatically update.

Change-Id: I1c1fe11b2096d6e2bdf578902e609b718c3bcb5c
Signed-off-by: James Kuszmaul <james.kuszmaul@bluerivertech.com>
diff --git a/aos/events/logging/logger_test.cc b/aos/events/logging/logger_test.cc
index f2cd702..5990a7a 100644
--- a/aos/events/logging/logger_test.cc
+++ b/aos/events/logging/logger_test.cc
@@ -545,10 +545,8 @@
         });
 
     constexpr std::chrono::microseconds kSendPeriod{10};
-    const int max_legal_messages =
-        ping_sender.channel()->frequency() *
-        event_loop_factory.configuration()->channel_storage_duration() /
-        1000000000;
+    const int max_legal_messages = configuration::QueueSize(
+        event_loop_factory.configuration(), ping_sender.channel());
 
     ping_spammer_event_loop->OnRun(
         [&ping_spammer_event_loop, kSendPeriod, timer_handler]() {