[DevTools] Fix race in testDeviceMetricsOverrides.

Source/devtools/front_end/Tests.js

 /*
  * Copyright (C) 2010 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 206 matching lines @@
         // In case of exception the override won't be called.
         try {
             override.apply(this, arguments);
         } catch (e) {
             test.fail("Exception in overriden method '" + methodName + "': " + e);
         }
         return result;
     };
 };
 
+/**
+ * Waits for current throttler invocations, if any.
+ * @param {!WebInspector.Throttler} throttler
+ * @param {!function} callback
+ */
+TestSuite.prototype.waitForThrottler = function(throttler, callback)
+{
+    var test = this;
+    var scheduleShouldFail = true;
+    test.addSniffer(throttler, "schedule", onSchedule);
+
+    function hasSomethingScheduled()
+    {
+        return throttler._isRunningProcess || throttler._process;
+    }
+
+    function checkState()
+    {
+        if (!hasSomethingScheduled()) {
+            scheduleShouldFail = false;
+            callback();
+            return;
+        }
+
+        test.addSniffer(throttler, "_processCompletedForTests", checkState);
+    }
+
+    function onSchedule()
+    {
+        if (scheduleShouldFail)
+            test.fail("Unexpected Throttler.schedule");
+    }
+
+    checkState();
+};
 
 // UI Tests
 
 
 /**
  * Tests that scripts tab can be open and populated with inspected scripts.
  */
 TestSuite.prototype.testShowScriptsTab = function()
 {
     this.showPanel("sources");
@@ skipping 371 matching lines @@
     function step4()
     {
         testOverrides({width: 1200, height: 1000, deviceScaleFactor: 3, mobile: false, fitWindow: false}, {width: 1200, height: 1000, deviceScaleFactor: 3}, finish);
     }
 
     function finish()
     {
         test.releaseControl();
     }
 
-    step1();
+    WebInspector.overridesSupport._deviceMetricsChangedListenerMuted = true;
     test.takeControl();
+    this.waitForThrottler(WebInspector.overridesSupport._deviceMetricsThrottler, step1);
 };
 
 TestSuite.prototype.waitForTestResultsInConsole = function()
 {
     var messages = WebInspector.multitargetConsoleModel.messages();
     for (var i = 0; i < messages.length; ++i) {
         var text = messages[i].messageText;
         if (text === "PASS")
             return;
         else if (/^FAIL/.test(text))
@@ skipping 253 matching lines @@
     delete uiTests._pendingTestName;
     if (name)
         new TestSuite().runTest(name);
 }
 
 WebInspector.notifications.addEventListener(WebInspector.NotificationService.Events.InspectorAgentEnabledForTests, runTests);
 
 })();
 
 }