[DevTools] unflake TestWindowInitializedOnNavigateBack

TBR=dgozman@chromium.org

Bug: chromium:628174
Change-Id: Ibee6850f5f58296eec80097dc2c74aa1237a6c31
Reviewed-on: https://chromium-review.googlesource.com/848321
Commit-Queue: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Reviewed-by: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#526751}

chrome/browser/devtools/devtools_sanity_browsertest.cc

@@ -2027,9 +2027,8 @@ class MockWebUIProvider
 // This tests checks that window is correctly initialized when DevTools is
 // opened while navigation through history with forward and back actions.
 // (crbug.com/627407)
-// Flaky on Windows and ChromeOS. http://crbug.com/628174#c4
 IN_PROC_BROWSER_TEST_F(DevToolsSanityTest,
-                       DISABLED_TestWindowInitializedOnNavigateBack) {
+                       TestWindowInitializedOnNavigateBack) {
   TestChromeWebUIControllerFactory test_factory;
   MockWebUIProvider mock_provider("dummyurl",
                                   "<script>\n"

third_party/WebKit/Source/devtools/front_end/Tests.js

@@ -902,11 +902,22 @@
   };
 
   TestSuite.prototype.testWindowInitializedOnNavigateBack = function() {
+    var test = this;
+    test.takeControl();
     var messages = ConsoleModel.consoleModel.messages();
-    this.assertEquals(1, messages.length);
-    var text = messages[0].messageText;
-    if (text.indexOf('Uncaught') !== -1)
-      this.fail(text);
+    if (messages.length === 1) {
+      checkMessages();
+    } else {
+      ConsoleModel.consoleModel.addEventListener(
+          ConsoleModel.ConsoleModel.Events.MessageAdded, checkMessages.bind(this), this);
+    }
+
+    function checkMessages() {
+      var messages = ConsoleModel.consoleModel.messages();
+      test.assertEquals(1, messages.length);
+      test.assertTrue(messages[0].messageText.indexOf('Uncaught') === -1);
+      test.releaseControl();
+    }
   };
 
   TestSuite.prototype.testConsoleContextNames = function() {