Add missing (and remove superfluous) 'explicit' from constructors.

chrome/browser/sync/profile_sync_service_bookmark_unittest.cc

 // Copyright (c) 2012 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.
 
 // TODO(akalin): This file is basically just a unit test for
 // BookmarkChangeProcessor.  Write unit tests for
 // BookmarkModelAssociator separately.
 
 #include <map>
 #include <queue>
@@ skipping 202 matching lines @@
 
   // The transaction on which everything happens.
   syncer::WriteTransaction *trans_;
 
   // The change list we construct.
   syncer::ChangeRecordList changes_;
 };
 
 class ExtensiveChangesBookmarkModelObserver : public BaseBookmarkModelObserver {
  public:
-  explicit ExtensiveChangesBookmarkModelObserver()
+  ExtensiveChangesBookmarkModelObserver()
       : started_count_(0),
         completed_count_at_started_(0),
         completed_count_(0) {}
 
   virtual void ExtensiveBookmarkChangesBeginning(
       BookmarkModel* model) OVERRIDE {
     ++started_count_;
     completed_count_at_started_ = completed_count_;
   }
 
@@ skipping 1512 matching lines @@
             new_versions[changed_bookmark->id()]);
   initial_versions.erase(changed_bookmark->id());
   ExpectTransactionVersionMatch(model_->bookmark_bar_node(), initial_versions);
   ExpectTransactionVersionMatch(model_->other_node(), initial_versions);
   ExpectTransactionVersionMatch(model_->mobile_node(), initial_versions);
 }
 
 }  // namespace
 
 }  // namespace browser_sync