Remove explicit keyword from multi-argument constructors

chrome/browser/plugin_data_remover_helper.cc

 // 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.
 
 #include "chrome/browser/plugin_data_remover_helper.h"
 
 #include <string>
 
 #include "base/memory/ref_counted.h"
 #include "chrome/browser/plugin_data_remover.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "content/browser/browser_thread.h"
 #include "content/common/notification_service.h"
 
 // The internal class is refcounted so it can outlive PluginDataRemoverHelper.
 class PluginDataRemoverHelper::Internal
     : public base::RefCountedThreadSafe<PluginDataRemoverHelper::Internal> {
  public:
-  explicit Internal(const char* pref_name, PrefService* prefs)
+  Internal(const char* pref_name, PrefService* prefs)
       : pref_name_(pref_name), prefs_(prefs) {}
 
   void StartUpdate() {
     BrowserThread::PostTask(
         BrowserThread::FILE,
         FROM_HERE,
         NewRunnableMethod(
             this,
             &PluginDataRemoverHelper::Internal::UpdateOnFileThread));
   }
@@ skipping 51 matching lines @@
 
 void PluginDataRemoverHelper::Observe(int type,
                                       const NotificationSource& source,
                                       const NotificationDetails& details) {
   if (type == content::NOTIFICATION_PLUGIN_ENABLE_STATUS_CHANGED) {
     internal_->StartUpdate();
   } else {
     NOTREACHED();
   }
 }