Merge "make shutdown safe for double calls."
am: 71fa1068de

Change-Id: I161c96dc5a44890fffe8fcdf9e0f8fc874df29c0
diff --git a/VolumeManager.cpp b/VolumeManager.cpp
index 4a649bb..927c660 100644
--- a/VolumeManager.cpp
+++ b/VolumeManager.cpp
@@ -633,8 +633,13 @@
     return 0;
 }
 
+// Can be called twice (sequentially) during shutdown. should be safe for that.
 int VolumeManager::shutdown() {
+    if (mInternalEmulated == nullptr) {
+        return 0; // already shutdown
+    }
     mInternalEmulated->destroy();
+    mInternalEmulated = nullptr;
     for (const auto& disk : mDisks) {
         disk->destroy();
     }