Make CSSValuePool thread local to ensure correct parsing in colors on workers

third_party/WebKit/Source/core/css/CSSValuePool.cpp

 /*
  * Copyright (C) 2011, 2012 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 16 matching lines @@
 
 #include "core/css/CSSValueList.h"
 #include "core/css/parser/CSSParser.h"
 #include "core/style/ComputedStyle.h"
 #include "wtf/Threading.h"
 
 namespace blink {
 
 CSSValuePool& cssValuePool()
 {
+    DCHECK(isMainThread());
     DEFINE_STATIC_LOCAL(CSSValuePool, pool, (new CSSValuePool));
     return pool;
 }
 
 CSSValuePool::CSSValuePool()
     : m_inheritedValue(CSSInheritedValue::create())
     , m_implicitInitialValue(CSSInitialValue::createImplicit())
     , m_explicitInitialValue(CSSInitialValue::createExplicit())
     , m_unsetValue(CSSUnsetValue::create())
     , m_colorTransparent(CSSColorValue::create(Color::transparent))
@@ skipping 25 matching lines @@
 {
     // These are the empty and deleted values of the hash table.
     if (rgbValue == Color::transparent)
         return m_colorTransparent;
     if (rgbValue == Color::white)
         return m_colorWhite;
     // Just because it is common.
     if (rgbValue == Color::black)
         return m_colorBlack;
 
-    if (!isMainThread()) {
-        // TODO (crbug.com/599659): Make CSS color parsing work properly in a
-        // worker thread.
-        // Currently, ColorValueCache is not thread-safe; so we avoid interacting
-        // with it on a non-main thread.
-        return CSSColorValue::create(rgbValue);
-    }
-
     // Just wipe out the cache and start rebuilding if it gets too big.
     const unsigned maximumColorCacheSize = 512;
     if (m_colorValueCache.size() > maximumColorCacheSize)
         m_colorValueCache.clear();
 
     RawPtr<CSSColorValue> dummyValue = nullptr;
     ColorValueCache::AddResult entry = m_colorValueCache.add(rgbValue, dummyValue);
     if (entry.isNewEntry)
         entry.storedValue->value = CSSColorValue::create(rgbValue);
 
@@ skipping 74 matching lines @@
     visitor->trace(m_colorWhite);
     visitor->trace(m_colorBlack);
     visitor->trace(m_pixelValueCache);
     visitor->trace(m_percentValueCache);
     visitor->trace(m_numberValueCache);
     visitor->trace(m_fontFaceValueCache);
     visitor->trace(m_fontFamilyValueCache);
 }
 
 } // namespace blink