Bug 1236380 - GMPStorage::mShutdown=true until Init() succeeds - r=cpearce

Initialize GMPStorage::mShutdown to true, so that if Init() has not completed
yet or if it failed, other methods will not try and access a null mStorage.

dom/media/gmp/GMPStorageParent.cpp

@@ -568,7 +568,7 @@ GMPStorageParent::GMPStorageParent(const nsCString& aNodeId,
                                    GMPParent* aPlugin)
   : mNodeId(aNodeId)
   , mPlugin(aPlugin)
-  , mShutdown(false)
+  , mShutdown(true)
 {
 }
 
@@ -602,6 +602,7 @@ GMPStorageParent::Init()
     mStorage = MakeUnique<GMPMemoryStorage>();
   }
 
+  mShutdown = false;
   return NS_OK;
 }
 

dom/media/gmp/GMPStorageParent.h

@@ -54,6 +54,7 @@ private:
 
   const nsCString mNodeId;
   RefPtr<GMPParent> mPlugin;
+  // True after Shutdown(), or if Init() has not completed successfully.
   bool mShutdown;
 };