Delay touching disks when secure keyguard showing.

We've tried our best to protect against malicious storage devices
with limited SELinux domains, but let's be even more paranoid and
refuse to look at disks inserted while a secure keyguard is
showing.  We'll gladly scan them right away once the user confirms
their credentials.

Test: builds, boots, manual testing
Bug: 68054513
Change-Id: I37fd6c25bbd6631fa4ba3f84e19384d746a22498
diff --git a/VoldNativeService.h b/VoldNativeService.h
index d107138..1359d90 100644
--- a/VoldNativeService.h
+++ b/VoldNativeService.h
@@ -43,6 +43,8 @@
     binder::Status onUserStarted(int32_t userId);
     binder::Status onUserStopped(int32_t userId);
 
+    binder::Status onSecureKeyguardStateChanged(bool isShowing);
+
     binder::Status partition(const std::string& diskId, int32_t partitionType, int32_t ratio);
     binder::Status forgetPartition(const std::string& partGuid, const std::string& fsUuid);