[test] lazily parse css style rules

third_party/WebKit/Source/core/css/parser/CSSParserImpl.cpp

Index: third_party/WebKit/Source/core/css/parser/CSSParserImpl.cpp
diff --git a/third_party/WebKit/Source/core/css/parser/CSSParserImpl.cpp b/third_party/WebKit/Source/core/css/parser/CSSParserImpl.cpp
index 59c96a646cdd6bc98f2765b1a43d5e7d62918f6a..030f2578bd32f309b4f859cb1bd053177f8a055f 100644
--- a/third_party/WebKit/Source/core/css/parser/CSSParserImpl.cpp
+++ b/third_party/WebKit/Source/core/css/parser/CSSParserImpl.cpp
@@ -172,12 +172,14 @@ void CSSParserImpl::parseStyleSheet(const String& string, const CSSParserContext
 
     TRACE_EVENT_BEGIN0("blink,blink_style", "CSSParserImpl::parseStyleSheet.parse");
     CSSParserImpl parser(context, styleSheet);
+    parser.enableLazyParsing();
     bool firstRuleValid = parser.consumeRuleList(scope.tokenRange(), TopLevelRuleList, [&styleSheet](StyleRuleBase* rule) {
         if (rule->isCharsetRule())
             return;
         styleSheet->parserAppendRule(rule);
     });
     styleSheet->setHasSyntacticallyValidCSSHeader(firstRuleValid);
+    styleSheet->populateStringPool(scope.stringPool());
     TRACE_EVENT_END0("blink,blink_style", "CSSParserImpl::parseStyleSheet.parse");
 
     TRACE_EVENT_END2(
@@ -276,6 +278,13 @@ void CSSParserImpl::parseDeclarationListForInspector(const String& declaration,
     parser.consumeDeclarationList(scope.tokenRange(), StyleRule::Style);
 }
 
+ImmutableStylePropertySet* CSSParserImpl::parseDeclarationListForLazyStyle(CSSParserTokenRange block, const CSSParserContext& context)
+{
+    CSSParserImpl parser(context);
+    parser.consumeDeclarationList(block, StyleRule::Style);
+    return createStylePropertySet(parser.m_parsedProperties, context.mode());
+}
+
 void CSSParserImpl::parseStyleSheetForInspector(const String& string, const CSSParserContext& context, StyleSheetContents* styleSheet, CSSParserObserver& observer)
 {
     CSSParserImpl parser(context, styleSheet);
@@ -684,8 +693,11 @@ StyleRule* CSSParserImpl::consumeStyleRule(CSSParserTokenRange prelude, CSSParse
     if (m_observerWrapper)
         observeSelectors(*m_observerWrapper, prelude);
 
+    // TODO(csharrison): How should we lazily parse css that needs the observer?
+    if (m_shouldUseLazyParsing && !m_observerWrapper) {
+        return StyleRule::createLazy(std::move(selectorList), block, &m_context);
+    }
     consumeDeclarationList(block, StyleRule::Style);
-
     return StyleRule::create(std::move(selectorList), createStylePropertySet(m_parsedProperties, m_context.mode()));
 }