Bug 1343212 - FilePicker child actor must not send Open() if it has been already distroyed, r=mccr8

widget/nsFilePickerProxy.h

@@ -60,6 +60,9 @@ private:
     ~nsFilePickerProxy();
     void InitNative(nsIWidget*, const nsAString&) override;
 
+    void
+    ActorDestroy(ActorDestroyReason aWhy) override;
+
     nsTArray<mozilla::dom::OwningFileOrDirectory> mFilesOrDirectories;
     nsCOMPtr<nsIFilePickerShownCallback> mCallback;
 
@@ -68,6 +71,8 @@ private:
     nsString  mDefault;
     nsString  mDefaultExtension;
 
+    bool mIPCActive;
+
     InfallibleTArray<nsString> mFilters;
     InfallibleTArray<nsString> mFilterNames;
 };