Backend for css rule tracking

third_party/WebKit/Source/devtools/front_end/sdk/CSSModel.js

 /*
  * Copyright (C) 2010 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 421 matching lines @@
       this._fireStyleSheetChanged(styleSheetId, edit);
       return true;
     }
 
     WebInspector.userMetrics.actionTaken(WebInspector.UserMetrics.Action.StyleRuleEdited);
     return this._ensureOriginalStyleSheetText(styleSheetId)
         .then(() => this._agent.setKeyframeKey(styleSheetId, range, text, callback.bind(this)))
         .catchException(false);
   }
 
+  startRuleUsageTracking() {
+    this._agent.startRuleUsageTracking();
+  }
+
+  /**
+   * @return {!Promise<?Array<!WebInspector.CSSModel.RuleUsageTracker>>}
+   */
+  ruleListPromise() {
+    /**
+     * @param {?string} error
+     * @param {!Array<!CSSAgent.RuleUsage>=} ruleUsage
+     * @return {?Array<!WebInspector.CSSModel.RuleUsageTracker>}
+     */
+    function usedRulesCallback(error, ruleUsage) {
+      if (error || !ruleUsage)
+        return null;
+
+      return ruleUsage.map(rule => ({range: rule.range, styleSheetId: rule.styleSheetId, wasUsed: rule.used}));
+    }
+
+    return this._agent.stopRuleUsageTracking(usedRulesCallback);
+  }
+
   /**
    * @return {!Promise.<!Array.<!WebInspector.CSSMedia>>}
    */
   mediaQueriesPromise() {
     /**
      * @param {?Protocol.Error} error
      * @param {?Array.<!CSSAgent.CSSMedia>} payload
      * @return {!Array.<!WebInspector.CSSMedia>}
      * @this {!WebInspector.CSSModel}
      */
@@ skipping 531 matching lines @@
       this._cachedMatchedCascadePromise = this.matchedStylesPromise(node.id);
     return this._cachedMatchedCascadePromise;
   }
 
   discardCachedMatchedCascade() {
     delete this._cachedMatchedCascadeNode;
     delete this._cachedMatchedCascadePromise;
   }
 };
 
+/** @typedef {!{range: !CSSAgent.SourceRange, styleSheetId: !CSSAgent.StyleSheetId, wasUsed: boolean}} */
+WebInspector.CSSModel.RuleUsageTracker;

[caseq, 2016/11/03 00:13:08]

Why is it called tracker? Is it tracking something? Let's call it just
WebInspector.CSSModel.RuleUsage

+
 /** @enum {symbol} */
 WebInspector.CSSModel.Events = {
   LayoutEditorChange: Symbol('LayoutEditorChange'),
   FontsUpdated: Symbol('FontsUpdated'),
   MediaQueryResultChanged: Symbol('MediaQueryResultChanged'),
   ModelWasEnabled: Symbol('ModelWasEnabled'),
   PseudoStateForced: Symbol('PseudoStateForced'),
   StyleSheetAdded: Symbol('StyleSheetAdded'),
   StyleSheetChanged: Symbol('StyleSheetChanged'),
   StyleSheetRemoved: Symbol('StyleSheetRemoved'),
@@ skipping 176 matching lines @@
 WebInspector.CSSModel.InlineStyleResult = class {
   /**
    * @param {?WebInspector.CSSStyleDeclaration} inlineStyle
    * @param {?WebInspector.CSSStyleDeclaration} attributesStyle
    */
   constructor(inlineStyle, attributesStyle) {
     this.inlineStyle = inlineStyle;
     this.attributesStyle = attributesStyle;
   }
 };