DevTools: Get rid of synchronous XHRs in the frontend code

Source/devtools/front_end/sources/ScriptFormatter.js

Index: Source/devtools/front_end/sources/ScriptFormatter.js
diff --git a/Source/devtools/front_end/sources/ScriptFormatter.js b/Source/devtools/front_end/sources/ScriptFormatter.js
index 13b0814a2c947a0ee229d27a3830737f25e1390f..285fc7099dc06854cc13379165c95e11a0b66d80 100644
--- a/Source/devtools/front_end/sources/ScriptFormatter.js
+++ b/Source/devtools/front_end/sources/ScriptFormatter.js
@@ -105,7 +105,7 @@ WebInspector.ScriptFormatter.prototype = {
         const method = "format";
         var parameters = { mimeType: mimeType, content: content, indentString: WebInspector.settings.textEditorIndent.get() };
         this._tasks.push({ data: parameters, callback: callback });
-        this._worker.postMessage({ method: method, params: parameters });
+        this._postMessage({ method: method, params: parameters });
     },
 
     _didFormatContent: function(event)
@@ -119,15 +119,40 @@ WebInspector.ScriptFormatter.prototype = {
     },
 
     /**
-     * @return {!Worker}
+     * @param {!Object} message
      */
-    get _worker()
+    _postMessage: function(message)
     {
-        if (!this._cachedWorker) {
-            this._cachedWorker = Runtime.startWorker("script_formatter_worker");
+        this._workerPromise().then(postMessage.bind(this));
+
+        /**
+         * @this {WebInspector.ScriptFormatter}
+         */
+        function postMessage()
+        {
+            this._cachedWorker.postMessage(message);

[pfeldman, 2014/11/10 10:23:26]

It would have deferred postMessage on its own.

+        }
+    },
+
+    /**
+     * @return {!Promise.<undefined>}
+     */
+    _workerPromise: function()
+    {
+        if (!this._pendingWorkerPromise)
+            this._pendingWorkerPromise = WorkerRuntime.startWorker("script_formatter_worker").then(started.bind(this));
+
+        return this._pendingWorkerPromise;
+
+        /**
+         * @param {!Worker} worker
+         * @this {WebInspector.ScriptFormatter}
+         */
+        function started(worker)
+        {
+            this._cachedWorker = worker;
             this._cachedWorker.onmessage = /** @type {function(this:Worker)} */ (this._didFormatContent.bind(this));
         }
-        return this._cachedWorker;
     }
 }