DevTools: liveSASS should tolerate race between iNotify and BrowserSync

third_party/WebKit/Source/devtools/front_end/sass/SASSSourceMapFactory.js

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * @constructor
  * @implements {WebInspector.SourceMapFactory}
  */
 WebInspector.SASSSourceMapFactory = function()
 {
     this._astService = new WebInspector.ASTService();
 }
 
 WebInspector.SASSSourceMapFactory.prototype = {
     /**
      * @override
      * @param {!WebInspector.Target} target
      * @param {!WebInspector.SourceMap} sourceMap
      * @return {!Promise<?WebInspector.SourceMap>}
      */
     editableSourceMap: function(target, sourceMap)
     {
         var cssModel = WebInspector.CSSModel.fromTarget(target);
         if (!cssModel)
             return Promise.resolve(/** @type {?WebInspector.SourceMap} */(null));
 
-        var headerIds = cssModel.styleSheetIdsForURL(sourceMap.compiledURL());
-        if (!headerIds || !headerIds.length)
+        var header = cssModel.styleSheetHeaders().find(styleSheetHeader => styleSheetHeader.sourceMapURL === sourceMap.url());
+        if (!header)
             return Promise.resolve(/** @type {?WebInspector.SourceMap} */(null));
-        var header = cssModel.styleSheetHeaderForId(headerIds[0]);
 
         /** @type {!Map<string, !WebInspector.SASSSupport.AST>} */
         var models = new Map();
         var promises = [];
         for (let url of sourceMap.sourceURLs()) {
             var contentProvider = sourceMap.sourceContentProvider(url, WebInspector.resourceTypes.SourceMapStyleSheet);
             var sassPromise = contentProvider.requestContent()
                 .then(text => this._astService.parseSCSS(url, text || ""))
                 .then(ast => models.set(ast.document.url, ast));
             promises.push(sassPromise);
@@ skipping 38 matching lines @@
             var sassNode = sassAST.findNodeForPosition(entry.sourceLineNumber, entry.sourceColumnNumber);
             if (!sassNode)
                 return;
             if (cssNode.parent && (cssNode.parent instanceof WebInspector.SASSSupport.Property) && cssNode === cssNode.parent.name)
                 valid = valid && cssNode.text.trim() === sassNode.text.trim();
             map.addMapping(cssNode, sassNode);
         }
     },
 }