DevTools: Get rid of synchronous XHRs in the frontend code

Source/devtools/front_end/profiler/HeapSnapshotProxy.js

Index: Source/devtools/front_end/profiler/HeapSnapshotProxy.js
diff --git a/Source/devtools/front_end/profiler/HeapSnapshotProxy.js b/Source/devtools/front_end/profiler/HeapSnapshotProxy.js
index 5f0324eb7e9091febe46a339f13a2dc9d72f2662..425491954acf03295923a4adddbbb67716fd5bd4 100644
--- a/Source/devtools/front_end/profiler/HeapSnapshotProxy.js
+++ b/Source/devtools/front_end/profiler/HeapSnapshotProxy.js
@@ -40,12 +40,34 @@ WebInspector.HeapSnapshotWorkerProxy = function(eventHandler)
     this._nextCallId = 1;
     this._callbacks = [];
     this._previousCallbacks = [];
-    this._worker = Runtime.startWorker("heap_snapshot_worker");
-    this._worker.onmessage = this._messageReceived.bind(this);
+    this._pendingMessages = [];
+    Runtime.startWorker("heap_snapshot_worker").then(this._init.bind(this)).done();
 }
 
 WebInspector.HeapSnapshotWorkerProxy.prototype = {
     /**
+     * @param {!Worker} worker
+     */
+    _init: function(worker)
+    {
+        this._worker = worker;
+        if (this._disposed) {
+            this.dispose();
+            return;
+        }
+        this._worker.onmessage = this._messageReceived.bind(this);
+        this._handlePendingMessages();
+    },
+
+    _handlePendingMessages: function()
+    {
+        for (var i = 0; i < this._pendingMessages.length; ++i)
+            this._worker.postMessage(this._pendingMessages[i]);
+
+        delete this._pendingMessages;
+    },
+
+    /**
      * @param {number} profileUid
      * @param {function(!WebInspector.HeapSnapshotProxy)} snapshotReceivedCallback
      * @return {!WebInspector.HeapSnapshotLoaderProxy}
@@ -60,7 +82,10 @@ WebInspector.HeapSnapshotWorkerProxy.prototype = {
 
     dispose: function()
     {
-        this._worker.terminate();
+        if (this._worker)
+            this._worker.terminate();
+        else
+            this._disposed = true;
         if (this._interval)
             clearInterval(this._interval);
     },
@@ -171,9 +196,15 @@ WebInspector.HeapSnapshotWorkerProxy.prototype = {
         callback(data.result);
     },
 
+    /**
+     * @param {!Object} message
+     */
     _postMessage: function(message)
     {
-        this._worker.postMessage(message);
+        if (this._worker)
+            this._worker.postMessage(message);
+        else
+            this._pendingMessages.push(message);

[pfeldman, 2014/11/07 14:51:17]

You should chain it to the _pendingWorkerPromise instead:

this._pendingWorkerPromise().then(postMessage.bind(this));
function postMessage()
{
    this._worker.postMessage(message);
}

[apavlov, 2014/11/10 07:44:11]

Done.

     },
 
     __proto__: WebInspector.Object.prototype
@@ -445,7 +476,7 @@ WebInspector.HeapSnapshotProxy.prototype = {
     },
 
     /**
-     * @param {!function(!WebInspector.HeapSnapshotCommon.Statistics):void} callback
+     * @param {function(!WebInspector.HeapSnapshotCommon.Statistics):void} callback
      */
     getStatistics: function(callback)
     {