Bug 1372405 - Delete default Runnable ctor so name must be provided (r=froydnj)

MozReview-Commit-ID: 9L4UoBJWzQ3

xpcom/threads/nsThreadUtils.h

@@ -382,7 +382,7 @@ public:
   NS_DECL_NSIRUNNABLE
   NS_DECL_NSINAMED
 
-  Runnable() {}
+  Runnable() = delete;
 
 #ifdef RELEASE_OR_BETA
   explicit Runnable(const char* aName) {}
@@ -412,7 +412,7 @@ public:
   // nsICancelableRunnable
   virtual nsresult Cancel() override;
 
-  CancelableRunnable() {}
+  CancelableRunnable() = delete;
   explicit CancelableRunnable(const char* aName) : Runnable(aName) {}
 
 protected: