Fix wording to comply with respectful-code

https://source.android.com/setup/contribute/respectful-code

Test: Run unit tests
Change-Id: Ia6647c9cf3224b962286151932118093b9ad979a
diff --git a/omaha_request_builder_xml.cc b/omaha_request_builder_xml.cc
index 097b9f1..e2857f1 100644
--- a/omaha_request_builder_xml.cc
+++ b/omaha_request_builder_xml.cc
@@ -216,7 +216,7 @@
     if (!prefs_->GetString(prefs_key, &cohort_value) || cohort_value.empty())
       return "";
   }
-  // This is a sanity check to avoid sending a huge XML file back to Ohama due
+  // This is a validity check to avoid sending a huge XML file back to Ohama due
   // to a compromised stateful partition making the update check fail in low
   // network environments envent after a reboot.
   if (cohort_value.size() > 1024) {