Don't generate RuleSets for viewport UA sheets.

third_party/WebKit/Source/core/css/resolver/ViewportStyleResolver.cpp

 /*
  * Copyright (C) 2012-2013 Intel Corporation. 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.
@@ skipping 15 matching lines @@
  * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
 
 #include "core/css/resolver/ViewportStyleResolver.h"
 
 #include "core/CSSValueKeywords.h"
 #include "core/css/CSSDefaultStyleSheets.h"
 #include "core/css/CSSPrimitiveValueMappings.h"
 #include "core/css/CSSToLengthConversionData.h"
+#include "core/css/MediaValuesDynamic.h"
 #include "core/css/StylePropertySet.h"
 #include "core/css/StyleRule.h"
+#include "core/css/StyleSheetContents.h"
 #include "core/css/resolver/ScopedStyleResolver.h"
 #include "core/dom/Document.h"
 #include "core/dom/NodeComputedStyle.h"
 #include "core/dom/ViewportDescription.h"
 #include "core/frame/Settings.h"
 #include "core/layout/api/LayoutViewItem.h"
 
 namespace blink {
 
-ViewportStyleResolver::ViewportStyleResolver(Document* document)
+ViewportStyleResolver::ViewportStyleResolver(Document& document)
     : m_document(document), m_hasAuthorStyle(false) {
-  ASSERT(m_document);
+  DCHECK(document.frame());
+  // TODO(rune@opera.com): The MediaValues object passed here should reflect the
+  // initial viewport, not the actual viewport. See https://crbug.com/332763
+  m_initialViewportMedium =
+      new MediaQueryEvaluator(MediaValuesDynamic::create(document.frame()));
 }
 
-void ViewportStyleResolver::collectViewportRules() {
+void ViewportStyleResolver::collectViewportRulesFromUASheets() {
   CSSDefaultStyleSheets& defaultStyleSheets = CSSDefaultStyleSheets::instance();
-  collectViewportRules(defaultStyleSheets.defaultStyle(), UserAgentOrigin);
-
   WebViewportStyle viewportStyle = m_document->settings()
                                        ? m_document->settings()->viewportStyle()
                                        : WebViewportStyle::Default;
-  RuleSet* viewportRules = nullptr;
+  StyleSheetContents* viewportContents = nullptr;
   switch (viewportStyle) {
     case WebViewportStyle::Default:
       break;
     case WebViewportStyle::Mobile:
-      viewportRules = defaultStyleSheets.defaultMobileViewportStyle();
+      viewportContents = defaultStyleSheets.ensureMobileViewportStyleSheet();
       break;
     case WebViewportStyle::Television:
-      viewportRules = defaultStyleSheets.defaultTelevisionViewportStyle();
+      viewportContents =
+          defaultStyleSheets.ensureTelevisionViewportStyleSheet();
       break;
   }
-  if (viewportRules)
-    collectViewportRules(viewportRules, UserAgentOrigin);
+  if (viewportContents)
+    collectViewportChildRules(viewportContents->childRules(), UserAgentOrigin);
 
-  if (m_document->isMobileDocument())
-    collectViewportRules(defaultStyleSheets.defaultXHTMLMobileProfileStyle(),
-                         UserAgentOrigin);
+  if (m_document->isMobileDocument()) {
+    collectViewportChildRules(
+        defaultStyleSheets.ensureXHTMLMobileProfileStyleSheet()->childRules(),
+        UserAgentOrigin);
+  }
+  DCHECK(!defaultStyleSheets.defaultStyleSheet()->hasViewportRule());
+}
 
+void ViewportStyleResolver::collectViewportRules() {
+  collectViewportRulesFromUASheets();
   if (ScopedStyleResolver* scopedResolver = m_document->scopedStyleResolver())
     scopedResolver->collectViewportRulesTo(this);
 
   resolve();
 }
 
+void ViewportStyleResolver::collectViewportChildRules(
+    const HeapVector<Member<StyleRuleBase>>& rules,
+    Origin origin) {
+  for (auto& rule : rules) {
+    if (rule->isViewportRule())
+      addViewportRule(*toStyleRuleViewport(rule), origin);
+    if (!rule->isMediaRule())

[Timothy Loh, 2016/10/14 04:27:24]

Also needs to recurse on @supports rules (this is eventually going to be used to
author sheets, right?)

[rune, 2016/10/14 07:59:02]

Oh, yes. Well spotted. And @import rules too, if their stylesheets contain
@viewport rules.

+      continue;
+    StyleRuleMedia* mediaRule = toStyleRuleMedia(rule);
+    if (!mediaRule->mediaQueries() ||
+        m_initialViewportMedium->eval(mediaRule->mediaQueries()))
+      collectViewportChildRules(mediaRule->childRules(), origin);
+  }
+}
+
 void ViewportStyleResolver::collectViewportRules(RuleSet* rules,
                                                  Origin origin) {
   rules->compactRulesIfNeeded();
 
   const HeapVector<Member<StyleRuleViewport>>& viewportRules =
       rules->viewportRules();
   for (size_t i = 0; i < viewportRules.size(); ++i)
-    addViewportRule(viewportRules[i], origin);
+    addViewportRule(*viewportRules[i], origin);
 }
 
-void ViewportStyleResolver::addViewportRule(StyleRuleViewport* viewportRule,
+void ViewportStyleResolver::addViewportRule(StyleRuleViewport& viewportRule,
                                             Origin origin) {
-  StylePropertySet& propertySet = viewportRule->mutableProperties();
+  StylePropertySet& propertySet = viewportRule.mutableProperties();
 
   unsigned propertyCount = propertySet.propertyCount();
   if (!propertyCount)
     return;
 
   if (origin == AuthorOrigin)
     m_hasAuthorStyle = true;
 
   if (!m_propertySet) {
     m_propertySet = propertySet.mutableCopy();
@@ skipping 123 matching lines @@
   Length result = primitiveValue->convertToLength(
       CSSToLengthConversionData(documentStyle, fontSizes, viewportSize, 1.0f));
   if (documentStyle->hasViewportUnits())
     m_document->setHasViewportUnits();
   documentStyle->setHasViewportUnits(documentStyleHasViewportUnits);
 
   return result;
 }
 
 DEFINE_TRACE(ViewportStyleResolver) {
+  visitor->trace(m_document);
   visitor->trace(m_propertySet);
-  visitor->trace(m_document);
+  visitor->trace(m_initialViewportMedium);
 }
 
 }  // namespace blink