Devtools [LayoutEditor]: Patch values in the selected rule

BUG=501896

Review URL: https://codereview.chromium.org/1310923003

git-svn-id: svn://svn.chromium.org/blink/trunk@201833 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/LayoutTests/inspector-protocol/css/css-set-effective-property-value-expected.txt

@@ -164,31 +164,6 @@ Running test: testChangeMissingProperty
         margin-top: 15px !important;
     }
 
-Running test: testChangeCSSOMEDProperty
-{
-    padding-top: 55px;
-    margin-top: 33px !important;
-    margin-bottom: 101px;
-}
-*#inspected* {    regular    readonly
-    margin-left: 10px;
-    margin-bottom: 10px;
-}
-*#inspected* {    regular
-    padding: 10px 20px 30px 40px;
-    padding-top: 50px;
-    padding-right: 20px;
-    padding-bottom: 30px;
-    padding-left: 40px;
-}
-@media (min-width: 1px)
-    *#inspected* {    regular
-        padding-left: 5px;
-        margin-left: 20px;
-        padding-left: 10px;
-        margin-top: 15px !important;
-    }
-
 Running test: testAppendWithSeparator
 Dumping inline style: 
 {

third_party/WebKit/LayoutTests/inspector-protocol/css/css-set-effective-property-value.html

@@ -73,16 +73,6 @@ function test()
             updateProperty("margin-bottom", "101px", dumpUndoAndNext(next));
         },
 
-        function testChangeCSSOMEDProperty(next)
-        {
-            InspectorTest.evaluateInInspectedPage("document.styleSheets[0].cssRules[0].style.marginBottom = \"10px\"", onEvaluate);
-
-            function onEvaluate()
-            {
-                updateProperty("margin-bottom", "101px", dumpUndoAndNext(next));
-            }
-        },
-
         function testAppendWithSeparator(next)
         {
 

third_party/WebKit/Source/core/inspector/InspectorCSSAgent.cpp

@@ -94,6 +94,32 @@ String createShorthandValue(Document* document, const String& shorthand, const S
     return style->getPropertyValue(shorthand);
 }
 
+PassRefPtrWillBeRawPtr<CSSRuleList> filterDuplicateRules(RefPtrWillBeRawPtr<CSSRuleList> ruleList)
+{
+    RefPtrWillBeRawPtr<StaticCSSRuleList> uniqRuleList = StaticCSSRuleList::create();
+    if (!ruleList)
+        return uniqRuleList.release();
+
+    HashSet<CSSStyleRule*> uniqRulesSet;
+
+    Vector<RefPtrWillBeRawPtr<CSSRule>> uniqRules;
+    for (unsigned i = ruleList->length(); i > 0; --i) {
+        CSSRule* rule = ruleList->item(i - 1);
+        if (!rule || rule->type() != CSSRule::STYLE_RULE)
+            continue;
+
+        CSSStyleRule* styleRule = toCSSStyleRule(rule);
+        if (uniqRulesSet.contains(styleRule))
+            continue;
+        uniqRulesSet.add(styleRule);
+        uniqRules.append(styleRule);
+    }
+
+    for (unsigned i = uniqRules.size(); i > 0; --i)
+        uniqRuleList->rules().append(uniqRules[i - 1]);
+    return uniqRuleList.release();
+}
+
 } // namespace
 
 namespace CSSAgentState {
@@ -1393,18 +1419,10 @@ PassRefPtr<TypeBuilder::Array<TypeBuilder::CSS::RuleMatch> > InspectorCSSAgent::
     if (!ruleList)
         return result.release();
 
-    HashSet<CSSStyleRule*> uniqRulesSet;
-    Vector<CSSStyleRule*> uniqRules;
-    for (unsigned i = ruleList->length(); i > 0; --i) {
-        CSSStyleRule* rule = asCSSStyleRule(ruleList->item(i - 1));
-        if (uniqRulesSet.contains(rule))
-            continue;
-        uniqRulesSet.add(rule);
-        uniqRules.append(rule);
-    }
+    RefPtrWillBeRawPtr<CSSRuleList> uniqRules = filterDuplicateRules(ruleList);
 
-    for (unsigned i = uniqRules.size(); i > 0; --i) {
-        CSSStyleRule* rule = uniqRules.at(i - 1);
+    for (unsigned i = 0; i < uniqRules->length(); ++i) {
+        CSSStyleRule* rule = asCSSStyleRule(uniqRules->item(i));
         RefPtr<TypeBuilder::CSS::CSSRule> ruleObject = buildObjectForRule(rule);
         if (!ruleObject)
             continue;
@@ -1515,11 +1533,9 @@ void InspectorCSSAgent::resetPseudoStates()
         document->setNeedsStyleRecalc(SubtreeStyleChange, StyleChangeReasonForTracing::create(StyleChangeReason::Inspector));
 }
 
-PassRefPtrWillBeRawPtr<CSSStyleDeclaration> InspectorCSSAgent::findEffectiveDeclaration(Element* element, CSSPropertyID propertyId)
+PassRefPtrWillBeRawPtr<CSSRuleList> InspectorCSSAgent::matchedRulesList(Element* element)
 {
     PseudoId elementPseudoId = element->pseudoId();
-    CSSStyleDeclaration* inlineStyle =  element->style();
-
     if (elementPseudoId) {
         element = element->parentOrShadowHostElement();
         if (!element)
@@ -1531,8 +1547,17 @@ PassRefPtrWillBeRawPtr<CSSStyleDeclaration> InspectorCSSAgent::findEffectiveDecl
     if (!ownerDocument->isActive())
         return nullptr;
 
-    String longhand = getPropertyNameString(propertyId);
+    StyleResolver& styleResolver = ownerDocument->ensureStyleResolver();
+    element->updateDistribution();
+    return filterDuplicateRules(styleResolver.pseudoCSSRulesForElement(element, elementPseudoId, StyleResolver::AllCSSRules));
+}
 
+PassRefPtrWillBeRawPtr<CSSStyleDeclaration> InspectorCSSAgent::findEffectiveDeclaration(CSSPropertyID propertyId, CSSRuleList* ruleList, CSSStyleDeclaration* inlineStyle)
+{
+    if (!ruleList && !inlineStyle)
+        return nullptr;
+
+    String longhand = getPropertyNameString(propertyId);
     RefPtrWillBeRawPtr<CSSStyleDeclaration> foundStyle = nullptr;
     bool isImportant = false;
 
@@ -1541,10 +1566,6 @@ PassRefPtrWillBeRawPtr<CSSStyleDeclaration> InspectorCSSAgent::findEffectiveDecl
         isImportant = inlineStyle->getPropertyPriority(longhand) == "important";
     }
 
-    StyleResolver& styleResolver = ownerDocument->ensureStyleResolver();
-    element->updateDistribution();
-    RefPtrWillBeRawPtr<CSSRuleList> ruleList = styleResolver.pseudoCSSRulesForElement(element, elementPseudoId, StyleResolver::AllCSSRules);
-
     for (unsigned i = 0, size = ruleList ? ruleList->length() : 0; i < size; ++i) {
         if (isImportant)
             break;
@@ -1571,39 +1592,16 @@ PassRefPtrWillBeRawPtr<CSSStyleDeclaration> InspectorCSSAgent::findEffectiveDecl
     return foundStyle.release();
 }
 
-void InspectorCSSAgent::setCSSPropertyValue(ErrorString* errorString, Element* element, CSSPropertyID propertyId, const String& value)
+void InspectorCSSAgent::setCSSPropertyValue(ErrorString* errorString, Element* element, RefPtrWillBeRawPtr<CSSStyleDeclaration> style, CSSPropertyID propertyId, const String& value, bool forceImportant)
 {
-    Document* ownerDocument = element->ownerDocument();
-    if (!ownerDocument->isActive()) {
-        *errorString = "Can't edit a node from a non-active document";
-        return;
-    }
-
-    Vector<StylePropertyShorthand, 4> shorthands;
-    getMatchingShorthandsForLonghand(propertyId, &shorthands);
-
-    String shorthand =  shorthands.size() > 0 ? getPropertyNameString(shorthands[0].id()) : String();
-    String longhand = getPropertyNameString(propertyId);
-
-    RefPtrWillBeRawPtr<CSSStyleDeclaration> foundStyle = findEffectiveDeclaration(element, propertyId);
-    CSSStyleDeclaration* inlineStyle =  element->style();
-    if (!foundStyle || !foundStyle->parentStyleSheet())
-        foundStyle = inlineStyle;
-
-    if (!foundStyle) {
-        *errorString = "Can't find a style to edit";
-        return;
-    }
-
     InspectorStyleSheetBase* inspectorStyleSheet =  nullptr;
     RefPtrWillBeRawPtr<CSSRuleSourceData> sourceData = nullptr;
-    if (foundStyle != inlineStyle) {
-        InspectorStyleSheet* styleSheet =  bindStyleSheet(foundStyle->parentStyleSheet());
+    // An absence of the parent rule means that given style is an inline style.
+    if (style->parentRule()) {
+        InspectorStyleSheet* styleSheet = bindStyleSheet(style->parentStyleSheet());
         inspectorStyleSheet = styleSheet;
-        sourceData = styleSheet->sourceDataForRule(foundStyle->parentRule());
-    }
-
-    if (!sourceData) {
+        sourceData = styleSheet->sourceDataForRule(style->parentRule());
+    } else {
         InspectorStyleSheetForInlineStyle* inlineStyleSheet = asInspectorStyleSheet(element);
         inspectorStyleSheet = inlineStyleSheet;
         sourceData = inlineStyleSheet->ruleSourceData();
@@ -1614,6 +1612,12 @@ void InspectorCSSAgent::setCSSPropertyValue(ErrorString* errorString, Element* e
         return;
     }
 
+    Vector<StylePropertyShorthand, 4> shorthands;
+    getMatchingShorthandsForLonghand(propertyId, &shorthands);
+
+    String shorthand =  shorthands.size() > 0 ? getPropertyNameString(shorthands[0].id()) : String();
+    String longhand = getPropertyNameString(propertyId);
+
     int foundIndex = -1;
     WillBeHeapVector<CSSPropertySourceData> properties = sourceData->styleSourceData->propertyData;
     for (unsigned i = 0; i < properties.size(); ++i) {
@@ -1638,8 +1642,7 @@ void InspectorCSSAgent::setCSSPropertyValue(ErrorString* errorString, Element* e
     String styleText = styleSheetText.substring(bodyRange.start, bodyRange.length());
     SourceRange changeRange;
     if (foundIndex == -1) {
-        bool isImportant = inlineStyle->getPropertyPriority(longhand) == "important";
-        String newPropertyText = "\n" + longhand + ": " + value + (isImportant ? " !important" : "") + ";";
+        String newPropertyText = "\n" + longhand + ": " + value + (forceImportant ? " !important" : "") + ";";
         if (!styleText.isEmpty() && !styleText.stripWhiteSpace().endsWith(';'))
             newPropertyText = ";" + newPropertyText;
         styleText.append(newPropertyText);
@@ -1649,11 +1652,11 @@ void InspectorCSSAgent::setCSSPropertyValue(ErrorString* errorString, Element* e
         CSSPropertySourceData declaration = properties[foundIndex];
         String newValueText;
         if (declaration.name == shorthand)
-            newValueText = createShorthandValue(ownerDocument, shorthand, declaration.value, longhand, value);
+            newValueText = createShorthandValue(element->ownerDocument(), shorthand, declaration.value, longhand, value);
         else
             newValueText = value;
 
-        String newPropertyText = declaration.name + ": " + newValueText + (declaration.important ? " !important" : "") + ";";
+        String newPropertyText = declaration.name + ": " + newValueText + (declaration.important || forceImportant ? " !important" : "") + ";";
         styleText.replace(declaration.range.start - bodyRange.start, declaration.range.length(), newPropertyText);
         changeRange.start = declaration.range.start;
         changeRange.end = changeRange.start + newPropertyText.length();
@@ -1667,6 +1670,7 @@ void InspectorCSSAgent::setCSSPropertyValue(ErrorString* errorString, Element* e
 
 void InspectorCSSAgent::setEffectivePropertyValueForNode(ErrorString* errorString, int nodeId, const String& propertyName, const String& value)
 {
+    // TODO: move testing from CSSAgent to layout editor.
     Element* element = elementForId(errorString, nodeId);
     if (!element)
         return;
@@ -1676,7 +1680,26 @@ void InspectorCSSAgent::setEffectivePropertyValueForNode(ErrorString* errorStrin
         *errorString = "Invalid property name";
         return;
     }
-    setCSSPropertyValue(errorString, element, cssPropertyID(propertyName), value);
+
+    Document* ownerDocument = element->ownerDocument();
+    if (!ownerDocument->isActive()) {
+        *errorString = "Can't edit a node from a non-active document";
+        return;
+    }
+
+    CSSPropertyID propertyId = cssPropertyID(propertyName);
+    CSSStyleDeclaration* inlineStyle = element->style();
+    RefPtrWillBeRawPtr<CSSRuleList> ruleList = matchedRulesList(element);
+    RefPtrWillBeRawPtr<CSSStyleDeclaration> foundStyle = findEffectiveDeclaration(propertyId, ruleList.get(), inlineStyle);
+    if (!foundStyle || !foundStyle->parentStyleSheet())
+        foundStyle = inlineStyle;
+
+    if (!foundStyle) {
+        *errorString = "Can't find a style to edit";
+        return;
+    }
+
+    setCSSPropertyValue(errorString, element, foundStyle.get(), propertyId, value);
 }
 
 DEFINE_TRACE(InspectorCSSAgent)

third_party/WebKit/Source/core/inspector/InspectorCSSAgent.h

@@ -115,7 +115,6 @@ public:
     void disable(ErrorString*) override;
     void reset();
     void mediaQueryResultChanged();
-    void setCSSPropertyValue(ErrorString*, Element*, CSSPropertyID, const String&);
 
     void activeStyleSheetsUpdated(Document*);
     void documentDetached(Document*);
@@ -145,8 +144,11 @@ public:
     void collectMediaQueriesFromStyleSheet(CSSStyleSheet*, TypeBuilder::Array<TypeBuilder::CSS::CSSMedia>* mediaArray);
     PassRefPtr<TypeBuilder::CSS::CSSMedia> buildMediaObject(const MediaList*, MediaListSource, const String&, CSSStyleSheet*);
     PassRefPtr<TypeBuilder::Array<TypeBuilder::CSS::CSSMedia> > buildMediaListChain(CSSRule*);
-    PassRefPtrWillBeRawPtr<CSSStyleDeclaration> findEffectiveDeclaration(Element*, CSSPropertyID);
 
+    PassRefPtrWillBeRawPtr<CSSStyleDeclaration> findEffectiveDeclaration(CSSPropertyID, CSSRuleList* matchedRulesList, CSSStyleDeclaration* inlineStyle);
+    void setCSSPropertyValue(ErrorString*, Element*, RefPtrWillBeRawPtr<CSSStyleDeclaration>, CSSPropertyID, const String& value, bool forceImportant = false);
+
+    PassRefPtrWillBeRawPtr<CSSRuleList> matchedRulesList(Element*);
 private:
     class StyleSheetAction;
     class SetStyleSheetTextAction;

third_party/WebKit/Source/core/inspector/LayoutEditor.cpp

@@ -8,7 +8,7 @@
 #include "core/css/CSSComputedStyleDeclaration.h"
 #include "core/css/CSSImportRule.h"
 #include "core/css/CSSMediaRule.h"
-#include "core/css/CSSRuleList.h"
+#include "core/css/CSSStyleRule.h"
 #include "core/css/MediaList.h"
 #include "core/dom/NodeComputedStyle.h"
 #include "core/dom/StaticNodeList.h"
@@ -145,11 +145,6 @@ float toValidValue(CSSPropertyID propertyId, float newValue)
     return newValue;
 }
 
-bool comparePairs(const std::pair<unsigned, CSSStyleRule*>& lhs, const std::pair<unsigned, CSSStyleRule*>& rhs)
-{
-    return lhs.first < rhs.first;
-}
-
 InspectorHighlightConfig affectedNodesHighlightConfig()
 {
     // TODO: find a better color
@@ -209,7 +204,8 @@ LayoutEditor::LayoutEditor(InspectorCSSAgent* cssAgent, InspectorDOMAgent* domAg
     , m_changingProperty(CSSPropertyInvalid)
     , m_propertyInitialValue(0)
     , m_isDirty(false)
-    , m_currentRuleIndex(-1)
+    , m_matchedRules(StaticCSSRuleList::create())
+    , m_currentRuleIndex(0)
 {
 }
 
@@ -231,7 +227,8 @@ void LayoutEditor::selectNode(Node* node)
     m_element = element;
     m_changingProperty = CSSPropertyInvalid;
     m_propertyInitialValue = 0;
-    initializeCSSRules();
+    m_matchedRules = m_cssAgent->matchedRulesList(m_element.get());
+    m_currentRuleIndex = m_matchedRules->length();
 }
 
 PassRefPtr<JSONObject> LayoutEditor::buildJSONInfo() const
@@ -265,7 +262,7 @@ PassRefPtr<JSONObject> LayoutEditor::buildJSONInfo() const
 
 RefPtrWillBeRawPtr<CSSPrimitiveValue> LayoutEditor::getPropertyCSSValue(CSSPropertyID property) const
 {
-    RefPtrWillBeRawPtr<CSSStyleDeclaration> style = m_cssAgent->findEffectiveDeclaration(m_element.get(), property);
+    RefPtrWillBeRawPtr<CSSStyleDeclaration> style = m_cssAgent->findEffectiveDeclaration(property, m_matchedRules.get(), m_element->style());
     if (!style)
         return nullptr;
 
@@ -332,11 +329,8 @@ void LayoutEditor::overlayStartedPropertyChange(const String& anchorName)
 void LayoutEditor::overlayPropertyChanged(float cssDelta)
 {
     if (m_changingProperty && m_factor) {
-        String errorString;
         float newValue = toValidValue(m_changingProperty, cssDelta / m_factor + m_propertyInitialValue);
-        m_cssAgent->setCSSPropertyValue(&errorString, m_element.get(), m_changingProperty, truncateZeroes(String::format("%.2f", newValue)) + CSSPrimitiveValue::unitTypeToString(m_valueUnitType));
-        if (!errorString)
-            m_isDirty = true;
+        m_isDirty |= setCSSPropertyValueInCurrentRule(truncateZeroes(String::format("%.2f", newValue)) + CSSPrimitiveValue::unitTypeToString(m_valueUnitType));
     }
 }
 
@@ -358,69 +352,29 @@ void LayoutEditor::clearSelection(bool commitChanges)
 
     m_element.clear();
     m_isDirty = false;
-    m_matchedRules.clear();
-    m_currentRuleIndex = -1;
+    m_matchedRules = StaticCSSRuleList::create();
+    m_currentRuleIndex = 0;
 }
 
-void LayoutEditor::initializeCSSRules()
+bool LayoutEditor::currentStyleIsInline()
 {
-    if (!m_element)
-        return;
-
-    Document* ownerDocument = m_element->ownerDocument();
-    // A non-active document has no styles.
-    if (!ownerDocument->isActive())
-        return;
-
-    // Matched rules.
-    StyleResolver& styleResolver = ownerDocument->ensureStyleResolver();
-    PseudoId elementPseudoId = m_element->pseudoId();
-    m_element->updateDistribution();
-    RefPtrWillBeRawPtr<CSSRuleList> matchedRules = styleResolver.pseudoCSSRulesForElement(m_element.get(), elementPseudoId, StyleResolver::AllCSSRules);
-    if (!matchedRules)
-        return;
-
-    HashSet<CSSStyleRule*> uniqRulesSet;
-    Vector<CSSStyleRule*> uniqRules;
-    for (unsigned i = matchedRules->length(); i > 0; --i) {
-        CSSRule* rule = matchedRules->item(i);
-        if (!rule || rule->type() != CSSRule::STYLE_RULE || !rule->parentStyleSheet())
-            continue;
-
-        CSSStyleRule* styleRule = toCSSStyleRule(rule);
-
-        if (uniqRulesSet.contains(styleRule))
-            continue;
-        uniqRulesSet.add(styleRule);
-        uniqRules.append(styleRule);
-    }
-    Vector<std::pair<unsigned, CSSStyleRule*>> selectors;
-    for (unsigned i = 0; i < uniqRules.size(); ++i) {
-        TrackExceptionState exceptionState;
-        RefPtrWillBeRawPtr<StaticElementList> elements = ownerDocument->querySelectorAll(AtomicString(uniqRules[i]->selectorText()), exceptionState);
-        unsigned length = exceptionState.hadException() ? 0: elements->length();
-        selectors.append(std::make_pair(length, uniqRules[i]));
-    }
-
-    std::sort(selectors.begin(), selectors.end(), &comparePairs);
-    for (size_t i = 0; i < selectors.size(); ++i)
-        m_matchedRules.append(selectors[i].second);
-};
+    return m_currentRuleIndex == m_matchedRules->length();
+}
 
 void LayoutEditor::nextSelector()
 {
-    if (static_cast<size_t>(m_currentRuleIndex + 1) == m_matchedRules.size())
+    if (m_currentRuleIndex == 0)
         return;
 
-    m_currentRuleIndex++;
+    m_currentRuleIndex--;
 }
 
 void LayoutEditor::previousSelector()
 {
-    if (m_currentRuleIndex == -1)
+    if (currentStyleIsInline())
         return;
 
-    m_currentRuleIndex--;
+    m_currentRuleIndex++;
 }
 
 String LayoutEditor::currentSelectorInfo()
@@ -429,35 +383,33 @@ String LayoutEditor::currentSelectorInfo()
         return String();
 
     RefPtr<JSONObject> object = JSONObject::create();
-    String currentSelectorText = m_currentRuleIndex == -1 ? "inline style" : m_matchedRules[m_currentRuleIndex]->selectorText();
+    String currentSelectorText = currentStyleIsInline() ? "inline style" : toCSSStyleRule(m_matchedRules->item(m_currentRuleIndex))->selectorText();
     object->setString("selector", currentSelectorText);
 
     Document* ownerDocument = m_element->ownerDocument();
-    if (!ownerDocument->isActive() || m_currentRuleIndex == -1)
+    if (!ownerDocument->isActive() || currentStyleIsInline())
         return object->toJSONString();
 
-    if (m_currentRuleIndex != -1) {
-        bool hasSameSelectors = false;
-        for (size_t i = 0; i < m_matchedRules.size(); i++) {
-            if (i != static_cast<unsigned>(m_currentRuleIndex) && m_matchedRules[i]->selectorText() == currentSelectorText) {
-                hasSameSelectors = true;
-                break;
-            }
+    bool hasSameSelectors = false;
+    for (unsigned i = 0; i < m_matchedRules->length(); i++) {
+        if (i != m_currentRuleIndex && toCSSStyleRule(m_matchedRules->item(i))->selectorText() == currentSelectorText) {
+            hasSameSelectors = true;
+            break;
         }
+    }
 
-        if (hasSameSelectors) {
-            Vector<String> medias;
-            buildMediaListChain(m_matchedRules[m_currentRuleIndex].get(), medias);
-            RefPtr<JSONArray> mediasJSONArray = JSONArray::create();
-            for (size_t i = 0; i < medias.size(); ++i)
-                mediasJSONArray->pushString(medias[i]);
+    if (hasSameSelectors) {
+        Vector<String> medias;
+        buildMediaListChain(m_matchedRules->item(m_currentRuleIndex), medias);
+        RefPtr<JSONArray> mediasJSONArray = JSONArray::create();
+        for (size_t i = 0; i < medias.size(); ++i)
+            mediasJSONArray->pushString(medias[i]);
 
-            object->setArray("medias", mediasJSONArray.release());
-        }
+        object->setArray("medias", mediasJSONArray.release());
     }
 
     TrackExceptionState exceptionState;
-    RefPtrWillBeRawPtr<StaticElementList> elements = ownerDocument->querySelectorAll(AtomicString(m_matchedRules[m_currentRuleIndex]->selectorText()), exceptionState);
+    RefPtrWillBeRawPtr<StaticElementList> elements = ownerDocument->querySelectorAll(AtomicString(currentSelectorText), exceptionState);
 
     if (!elements || exceptionState.hadException())
         return object->toJSONString();
@@ -477,4 +429,35 @@ String LayoutEditor::currentSelectorInfo()
     return object->toJSONString();
 }
 
+bool LayoutEditor::setCSSPropertyValueInCurrentRule(const String& value)
+{
+    if (!m_element)
+        return false;
+
+    RefPtrWillBeRawPtr<CSSStyleDeclaration> effectiveDeclaration = m_cssAgent->findEffectiveDeclaration(m_changingProperty, m_matchedRules.get(), m_element->style());
+    bool forceImportant = false;
+
+    if (effectiveDeclaration) {
+        CSSStyleRule* effectiveRule = nullptr;
+        if (effectiveDeclaration->parentRule() && effectiveDeclaration->parentRule()->type() == CSSRule::STYLE_RULE)
+            effectiveRule = toCSSStyleRule(effectiveDeclaration->parentRule());
+
+        unsigned effectiveRuleIndex = m_matchedRules->length();
+        for (unsigned i = 0; i < m_matchedRules->length(); ++i) {
+            if (m_matchedRules->item(i) == effectiveRule) {
+                effectiveRuleIndex = i;
+                break;
+            }
+        }
+        forceImportant = effectiveDeclaration->getPropertyPriority(getPropertyNameString(m_changingProperty)) == "important";
+        forceImportant |= effectiveRuleIndex > m_currentRuleIndex;
+    }
+
+    CSSStyleDeclaration* style = currentStyleIsInline() ? m_element->style() : toCSSStyleRule(m_matchedRules->item(m_currentRuleIndex))->style();
+
+    String errorString;
+    m_cssAgent->setCSSPropertyValue(&errorString, m_element.get(), style, m_changingProperty, value, forceImportant);
+    return errorString.isEmpty();
+}
+
 } // namespace blink

third_party/WebKit/Source/core/inspector/LayoutEditor.h

@@ -8,7 +8,7 @@
 #include "core/CSSPropertyNames.h"
 #include "core/CoreExport.h"
 #include "core/css/CSSPrimitiveValue.h"
-#include "core/css/CSSStyleRule.h"
+#include "core/css/CSSRuleList.h"
 #include "core/dom/Element.h"
 #include "platform/heap/Handle.h"
 #include "wtf/PassOwnPtr.h"
@@ -49,7 +49,8 @@ private:
     RefPtrWillBeRawPtr<CSSPrimitiveValue> getPropertyCSSValue(CSSPropertyID) const;
     PassRefPtr<JSONObject> createValueDescription(const String&) const;
     void appendAnchorFor(JSONArray*, const String&, const String&, const FloatPoint&, const FloatPoint&) const;
-    void initializeCSSRules();
+    bool setCSSPropertyValueInCurrentRule(const String&);
+    bool currentStyleIsInline();
 
     RefPtrWillBeMember<Element> m_element;
     RawPtrWillBeMember<InspectorCSSAgent> m_cssAgent;
@@ -60,9 +61,9 @@ private:
     CSSPrimitiveValue::UnitType m_valueUnitType;
     bool m_isDirty;
 
-    WillBeHeapVector<RefPtrWillBeMember<CSSStyleRule>> m_matchedRules;
-    // -1 means "inline style".
-    int m_currentRuleIndex;
+    RefPtrWillBeRawPtr<CSSRuleList> m_matchedRules;
+    // When m_currentRuleIndex == m_matchedRules.length(), current style is inline style.
+    unsigned m_currentRuleIndex;
 };
 
 } // namespace blink