Add base::RunLoop and update ui_test_utils to use it to reduce flakiness

chrome/browser/extensions/extension_browsertest.cc

Index: chrome/browser/extensions/extension_browsertest.cc
diff --git a/chrome/browser/extensions/extension_browsertest.cc b/chrome/browser/extensions/extension_browsertest.cc
index 50365fefb9743327d6d2369bc12e637e0783167f..c38b3bf28830df8244d34958c25ac77ee6622552 100644
--- a/chrome/browser/extensions/extension_browsertest.cc
+++ b/chrome/browser/extensions/extension_browsertest.cc
@@ -139,6 +139,10 @@ const Extension* ExtensionBrowserTest::LoadExtensionWithOptions(
     }
   }
 
+  // After chrome::NOTIFICATION_EXTENSION_LOADED there are still remaining tasks

[Paweł Hajdan Jr., 2012/06/18 15:56:25]

Have you checked all tests where we wait for NOTIFICATION_EXTENSION_LOADED? Just
checking.

[jbates, 2012/06/18 23:14:03]

Removed to see if reposting Quit task is enough.

+  // that need to complete for extensions to be in a settled load state.
+  ui_test_utils::RunAllPendingInMessageLoop();
+
   if (!WaitForExtensionViewsToLoad())
     return NULL;