Fix MQEvaluator::mediaType() related perf regressions.

Source/core/css/resolver/StyleResolver.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
@@ skipping 13 matching lines @@
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */
 
 #include "config.h"
 #include "core/css/resolver/StyleResolver.h"
 
 #include "core/CSSPropertyNames.h"
 #include "core/HTMLNames.h"
+#include "core/MediaTypeNames.h"
 #include "core/StylePropertyShorthand.h"
 #include "core/animation/ActiveAnimations.h"
 #include "core/animation/Animation.h"
 #include "core/animation/AnimationTimeline.h"
 #include "core/animation/StyleInterpolation.h"
 #include "core/animation/animatable/AnimatableValue.h"
 #include "core/animation/css/CSSAnimatableValueFactory.h"
 #include "core/animation/css/CSSAnimations.h"
 #include "core/css/CSSCalculationValue.h"
 #include "core/css/CSSDefaultStyleSheets.h"
@@ skipping 81 matching lines @@
 {
     RefPtrWillBeRawPtr<FontFace> fontFace = FontFace::create(document, fontFaceRule);
     if (fontFace)
         cssFontSelector->fontFaceCache()->add(cssFontSelector, fontFaceRule, fontFace);
 }
 
 StyleResolver::StyleResolver(Document& document)
     : m_document(document)
     , m_viewportStyleResolver(ViewportStyleResolver::create(&document))
     , m_needCollectFeatures(false)
+    , m_printMediaType(false)
     , m_styleResourceLoader(document.fetcher())
     , m_styleSharingDepth(0)
     , m_styleResolverStatsSequence(0)
     , m_accessCount(0)
 {
     FrameView* view = document.view();
-    if (view)
+    if (view) {
         m_medium = adoptPtr(new MediaQueryEvaluator(&view->frame()));
-    else
+        m_printMediaType = equalIgnoringCase(view->mediaType(), MediaTypeNames::print);

[esprehn, 2014/08/11 20:33:21]

Do we destroy the StyleResolver when the media type changes from non-print to
print and then back?

+    } else {
         m_medium = adoptPtr(new MediaQueryEvaluator("all"));
+    }
 
     initWatchedSelectorRules(CSSSelectorWatch::from(document).watchedCallbackSelectors());
 
 #if ENABLE(SVG_FONTS)
     if (document.svgExtensions()) {
         const WillBeHeapHashSet<RawPtrWillBeMember<SVGFontFaceElement> >& svgFontFaceElements = document.svgExtensions()->svgFontFaceElements();
         WillBeHeapHashSet<RawPtrWillBeMember<SVGFontFaceElement> >::const_iterator end = svgFontFaceElements.end();
         for (WillBeHeapHashSet<RawPtrWillBeMember<SVGFontFaceElement> >::const_iterator it = svgFontFaceElements.begin(); it != end; ++it)
             addFontFaceRule(&document, document.styleEngine()->fontSelector(), (*it)->fontFaceRule());
     }
@@ skipping 294 matching lines @@
     collector.collectMatchingRules(matchRequest, ruleRange);
 
     collector.sortAndTransferMatchedRules();
 }
 
 void StyleResolver::matchUARules(ElementRuleCollector& collector)
 {
     collector.setMatchingUARules(true);
 
     CSSDefaultStyleSheets& defaultStyleSheets = CSSDefaultStyleSheets::instance();
-    RuleSet* userAgentStyleSheet = m_medium->mediaTypeMatchSpecific("print")
-        ? defaultStyleSheets.defaultPrintStyle() : defaultStyleSheets.defaultStyle();
+    RuleSet* userAgentStyleSheet = m_printMediaType ? defaultStyleSheets.defaultPrintStyle() : defaultStyleSheets.defaultStyle();
     matchUARules(collector, userAgentStyleSheet);
 
     // In quirks mode, we match rules from the quirks user agent sheet.
     if (document().inQuirksMode())
         matchUARules(collector, defaultStyleSheets.defaultQuirksStyle());
 
     // If document uses view source styles (in view source mode or in xml viewer mode), then we match rules from the view source style sheet.
     if (document().isViewSource())
         matchUARules(collector, defaultStyleSheets.defaultViewSourceStyle());
 
@@ skipping 1129 matching lines @@
     visitor->trace(m_uncommonAttributeRuleSet);
     visitor->trace(m_watchedSelectorsRules);
     visitor->trace(m_treeBoundaryCrossingRules);
     visitor->trace(m_styleSharingLists);
     visitor->trace(m_pendingStyleSheets);
     visitor->trace(m_document);
 #endif
 }
 
 } // namespace blink