Store custom property backing strings in resolved CSSVariableData objects.

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CSSVariableData_h
 #define CSSVariableData_h
 
 #include "core/css/parser/CSSParserToken.h"
 #include "core/css/parser/CSSParserTokenRange.h"
 #include "wtf/RefCounted.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
 class CSSParserTokenRange;
 
 class CSSVariableData : public RefCounted<CSSVariableData> {
     WTF_MAKE_NONCOPYABLE(CSSVariableData);
     USING_FAST_MALLOC(CSSVariableData);
 public:
     static PassRefPtr<CSSVariableData> create(const CSSParserTokenRange& range, bool needsVariableResolution = true)
     {
         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; }
 
     const Vector<CSSParserToken>& tokens() { return m_tokens; }
 
     bool needsVariableResolution() const { return m_needsVariableResolution; }
 private:
     CSSVariableData(const CSSParserTokenRange&, bool needsVariableResolution);
 
     // We can safely copy the tokens (which have raw pointers to substrings) because
     // 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)
     { }
 
     void consumeAndUpdateTokens(const CSSParserTokenRange&);
     template<typename CharacterType> void updateTokens(const CSSParserTokenRange&);
 
     String m_backingString;
     Vector<CSSParserToken> m_tokens;
     const bool m_needsVariableResolution;
 };
 
 } // namespace blink
 
 #endif // CSSVariableData_h