DevTools: fix 'Failed to write into a temp file' when recording a filmstrip

Source/devtools/front_end/sdk/TracingModel.js

 /*
  * Copyright 2014 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
  * @param {!WebInspector.BackingStorage} backingStorage
  */
 WebInspector.TracingModel = function(backingStorage)
 {
+    this.reset();
+    // Set backing storage after reset so that we do not perform
+    // an extra reset of backing storage -- this is not free.
     this._backingStorage = backingStorage;
-    this.reset();
 }
 
 /**
  * @enum {string}
  */
 WebInspector.TracingModel.Phase = {
     Begin: "B",
     End: "E",
     Complete: "X",
     Instant: "I",
@@ skipping 158 matching lines @@
     },
 
     reset: function()
     {
         /** @type {!Object.<(number|string), !WebInspector.TracingModel.Process>} */
         this._processById = {};
         this._processByName = new Map();
         this._minimumRecordTime = 0;
         this._maximumRecordTime = 0;
         this._devToolsMetadataEvents = [];
-        this._backingStorage.reset();
+        if (this._backingStorage)
+            this._backingStorage.reset();
         this._appendDelimiter = false;
         /** @type {!Array<!WebInspector.TracingModel.Event>} */
         this._asyncEvents = [];
         /** @type {!Map<string, !WebInspector.TracingModel.AsyncEvent>} */
         this._openAsyncEvents = new Map();
         /** @type {!Map<string, !Array<!WebInspector.TracingModel.AsyncEvent>>} */
         this._openNestableAsyncEvents = new Map();
         /** @type {!Map<string, !Set<string>>} */
         this._parsedCategories = new Map();
     },
@@ skipping 714 matching lines @@
     /**
      * @return {!Array.<!WebInspector.TracingModel.AsyncEvent>}
      */
     asyncEvents: function()
     {
         return this._asyncEvents;
     },
 
     __proto__: WebInspector.TracingModel.NamedObject.prototype
 }