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

chrome/test/base/bookmark_load_observer.h

 // Copyright (c) 2011 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.
 
 #ifndef CHROME_TEST_BASE_BOOKMARK_LOAD_OBSERVER_H_
 #define CHROME_TEST_BASE_BOOKMARK_LOAD_OBSERVER_H_
 #pragma once
 
 #include "base/basictypes.h"
+#include "base/callback.h"
 #include "base/compiler_specific.h"
+#include "base/memory/weak_ptr.h"
 #include "chrome/browser/bookmarks/bookmark_model_observer.h"
 
 // BookmarkLoadObserver is used when blocking until the BookmarkModel
 // finishes loading. As soon as the BookmarkModel finishes loading the message
 // loop is quit.
 class BookmarkLoadObserver : public BookmarkModelObserver {
  public:
-  BookmarkLoadObserver();
+  explicit BookmarkLoadObserver(const base::Closure& quit_task);
   virtual ~BookmarkLoadObserver();
 
   virtual void Loaded(BookmarkModel* model, bool ids_reassigned) OVERRIDE;
   virtual void BookmarkNodeMoved(BookmarkModel* model,
                                  const BookmarkNode* old_parent,
                                  int old_index,
                                  const BookmarkNode* new_parent,
                                  int new_index) OVERRIDE {}
   virtual void BookmarkNodeAdded(BookmarkModel* model,
                                  const BookmarkNode* parent,
                                  int index)  OVERRIDE{}
   virtual void BookmarkNodeRemoved(BookmarkModel* model,
                                    const BookmarkNode* parent,
                                    int old_index,
                                    const BookmarkNode* node) OVERRIDE {}
   virtual void BookmarkNodeChanged(BookmarkModel* model,
                                    const BookmarkNode* node) OVERRIDE {}
   virtual void BookmarkNodeChildrenReordered(
       BookmarkModel* model,
       const BookmarkNode* node) OVERRIDE {}
   virtual void BookmarkNodeFaviconChanged(BookmarkModel* model,
                                           const BookmarkNode* node) OVERRIDE {}
 
  private:
+  base::Closure quit_task_;
   DISALLOW_COPY_AND_ASSIGN(BookmarkLoadObserver);
 };
 
 #endif  // CHROME_TEST_BASE_BOOKMARK_LOAD_OBSERVER_H_