Fix for flaky ExtensionBrowserTest.Popup test

chrome/browser/extensions/extension_browsertest.cc

 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/extensions/extension_browsertest.h"
 
 #include <vector>
 
 #include "base/command_line.h"
 #include "base/file_path.h"
@@ skipping 167 matching lines @@
     }
 
     MessageLoop::current()->PostDelayedTask(FROM_HERE,
                                             new MessageLoop::QuitTask, 200);
     ui_test_utils::RunMessageLoop();
   }
 }
 
 bool ExtensionBrowserTest::WaitForExtensionHostsToLoad() {
   // Wait for all the extension hosts that exist to finish loading.
-  // NOTE: This assumes that the extension host list is not changing while
-  // this method is running.
-
   NotificationRegistrar registrar;
   registrar.Add(this, NotificationType::EXTENSION_HOST_DID_STOP_LOADING,
                 NotificationService::AllSources());
 
   ExtensionProcessManager* manager =
         browser()->profile()->GetExtensionProcessManager();
   for (ExtensionProcessManager::const_iterator iter = manager->begin();
        iter != manager->end();) {
-    if ((*iter)->did_stop_loading())
+    if ((*iter)->did_stop_loading()) {
       ++iter;
-    else
+    } else {
       ui_test_utils::RunMessageLoop();
+
+      // Test activity may have modified the set of extension processes during
+      // message processing, so re-start the iteration to catch added/removed
+      // processes.
+      iter = manager->begin();
+    }
   }
   LOG(INFO) << "All ExtensionHosts loaded";
 
   return true;
 }
 
 bool ExtensionBrowserTest::WaitForExtensionInstall() {
   int before = extension_installs_observed_;
   ui_test_utils::RegisterAndWait(NotificationType::EXTENSION_INSTALLED, this,
                                  kTimeoutMs);
@@ skipping 41 matching lines @@
     case NotificationType::EXTENSION_OVERINSTALL_ERROR:
       std::cout << "Got EXTENSION_OVERINSTALL_ERROR notification.\n";
       MessageLoopForUI::current()->Quit();
       break;
 
     default:
       NOTREACHED();
       break;
   }
 }