Store custom property backing strings in resolved CSSVariableData objects.

third_party/WebKit/Source/core/css/CSSVariableData.h

Index: third_party/WebKit/Source/core/css/CSSVariableData.h
diff --git a/third_party/WebKit/Source/core/css/CSSVariableData.h b/third_party/WebKit/Source/core/css/CSSVariableData.h
index 9b350338e285513065ce3200fb5dc244ba6951cf..2bfe8265308a399215933874bd2387112af5bec4 100644
--- a/third_party/WebKit/Source/core/css/CSSVariableData.h
+++ b/third_party/WebKit/Source/core/css/CSSVariableData.h
@@ -23,9 +23,9 @@ public:
         return adoptRef(new CSSVariableData(range, needsVariableResolution));
     }
 
-    static PassRefPtr<CSSVariableData> createResolved(const Vector<CSSParserToken>& resolvedTokens)
+    static PassRefPtr<CSSVariableData> createResolved(const Vector<CSSParserToken>& resolvedTokens, PassRefPtr<CSSVariableData> unresolvedData)
     {
-        return adoptRef(new CSSVariableData(resolvedTokens));
+        return adoptRef(new CSSVariableData(resolvedTokens, unresolvedData->m_backingString));
     }
 
     CSSParserTokenRange tokenRange() { return m_tokens; }
@@ -40,8 +40,9 @@ private:
     // StylePropertySets contain references to CSSCustomPropertyDeclarations, which
     // point to the unresolved CSSVariableData values that own the backing strings
     // this will potentially reference.

[alancutter (OOO until 2018), 2015/12/03 04:14:12]

We should update the comment to the new lifetime guarantee rationale now that we
no longer depend on the relative life span of CSSCustomPropertyDeclarations.

[shans, 2015/12/03 04:29:55]

This comment isn't wrong..

I think I'll submit (probably as a separate patch) some fairly extensive
documentation improvements.

-    CSSVariableData(const Vector<CSSParserToken>& resolvedTokens)
-        : m_tokens(resolvedTokens)
+    CSSVariableData(const Vector<CSSParserToken>& resolvedTokens, String backingString)
+        : m_backingString(backingString)
+        , m_tokens(resolvedTokens)
         , m_needsVariableResolution(false)
     { }