Bug 1358968 - Part 4: Give nsComboboxDisplayFrame a name in frame tree dumps. r=bz

MozReview-Commit-ID: 67FhXW1C8lG

--HG--
extra : rebase_source : 68fdbcbc12b5928cc9f3f3924a9689809cdd0027

layout/forms/nsComboboxControlFrame.cpp

@@ -1292,6 +1292,13 @@ public:
   // depends on the available inline size.
   virtual nsIAtom* GetType() const override;
 
+#ifdef DEBUG_FRAME_DUMP
+  nsresult GetFrameName(nsAString& aResult) const
+  {
+    return MakeFrameName(NS_LITERAL_STRING("ComboboxDisplay"), aResult);
+  }
+#endif
+
   virtual bool IsFrameOfType(uint32_t aFlags) const override
   {
     return nsBlockFrame::IsFrameOfType(aFlags &