Bug 1296990 - Make AppearanceString() return nsAutoString directly. r=mtseng

MozReview-Commit-ID: IQ3KrFnCswx

--HG--
extra : rebase_source : ed646cc89797c104708c55d50a058ddd6c76b5bd

layout/base/AccessibleCaret.cpp

@@ -142,7 +142,7 @@ AccessibleCaret::SetSelectionBarEnabled(bool aEnabled)
   mSelectionBarEnabled = aEnabled;
 }
 
-/* static */ nsString
+/* static */ nsAutoString
 AccessibleCaret::AppearanceString(Appearance aAppearance)
 {
   nsAutoString string;

layout/base/AccessibleCaret.h

@@ -181,8 +181,8 @@ protected:
 
   nsIFrame* CustomContentContainerFrame() const;
 
-  // Transform Appearance to CSS class name in ua.css.
-  static nsString AppearanceString(Appearance aAppearance);
+  // Transform Appearance to CSS id used in ua.css.
+  static nsAutoString AppearanceString(Appearance aAppearance);
 
   already_AddRefed<dom::Element> CreateCaretElement(nsIDocument* aDocument) const;