DevTools: Throttle file system refreshes on focus.

Source/devtools/front_end/sdk/IsolatedFileSystem.js

 /*
  * Copyright (C) 2013 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 91 matching lines @@
     /**
      * @param {function(?DOMFileSystem)} callback
      */
     _requestFileSystem: function(callback)
     {
         this._manager.requestDOMFileSystem(this._path, callback);
     },
 
     /**
      * @param {string} path
-     * @param {function(string)} callback
+     * @param {function(string)} fileCallback
+     * @param {function()=} finishedCallback
      */
-    requestFilesRecursive: function(path, callback)
+    requestFilesRecursive: function(path, fileCallback, finishedCallback)
     {
         this._requestFileSystem(fileSystemLoaded.bind(this));
 
         var domFileSystem;
+        var pendingRequests = 0;
         /**
          * @param {?DOMFileSystem} fs
          * @this {WebInspector.IsolatedFileSystem}
          */
         function fileSystemLoaded(fs)
         {
             domFileSystem = /** @type {!DOMFileSystem} */ (fs);
             console.assert(domFileSystem);
+            ++pendingRequests;
             this._requestEntries(domFileSystem, path, innerCallback.bind(this));
         }
 
         /**
          * @param {!Array.<!FileEntry>} entries
          * @this {WebInspector.IsolatedFileSystem}
          */
         function innerCallback(entries)
         {
             for (var i = 0; i < entries.length; ++i) {
                 var entry = entries[i];
                 if (!entry.isDirectory) {
                     if (this._manager.mapping().isFileExcluded(this._path, entry.fullPath))
                         continue;
-                    callback(entry.fullPath.substr(1));
+                    fileCallback(entry.fullPath.substr(1));
                 }
                 else {
                     if (this._manager.mapping().isFileExcluded(this._path, entry.fullPath + "/"))
                         continue;
+                    ++pendingRequests;
                     this._requestEntries(domFileSystem, entry.fullPath, innerCallback.bind(this));
                 }
             }
+            if (finishedCallback && (--pendingRequests === 0))
+                finishedCallback();
         }
     },
 
     /**
      * @param {string} path
      * @param {?string} name
      * @param {function(?string)} callback
      */
     createFile: function(path, name, callback)
     {
@@ skipping 416 matching lines @@
         }
 
         function errorHandler(error)
         {
             var errorMessage = WebInspector.IsolatedFileSystem.errorMessage(error);
             console.error(errorMessage + " when requesting entry '" + path + "'");
             callback([]);
         }
     }
 }