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

chrome/browser/extensions/api/downloads/downloads_api.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.
 
 #include "chrome/browser/extensions/api/downloads/downloads_api.h"
 
 #include <algorithm>
 #include <cctype>
 #include <iterator>
 #include <set>
@@ skipping 513 matching lines @@
 }
 
 class ExtensionDownloadsEventRouterData : public base::SupportsUserData::Data {
  public:
   static ExtensionDownloadsEventRouterData* Get(DownloadItem* download_item) {
     base::SupportsUserData::Data* data = download_item->GetUserData(kKey);
     return (data == NULL) ? NULL :
         static_cast<ExtensionDownloadsEventRouterData*>(data);
   }
 
-  explicit ExtensionDownloadsEventRouterData(
+  ExtensionDownloadsEventRouterData(
       DownloadItem* download_item,
       scoped_ptr<base::DictionaryValue> json_item)
       : updated_(0),
         changed_fired_(0),
         json_(json_item.Pass()) {
     download_item->SetUserData(kKey, this);
   }
 
   virtual ~ExtensionDownloadsEventRouterData() {
     if (updated_ > 0) {
@@ skipping 502 matching lines @@
   if (profile_->HasOffTheRecordProfile() &&
       !profile_->IsOffTheRecord()) {
     DispatchEventInternal(
         profile_->GetOffTheRecordProfile(),
         event_name,
         json_args,
         scoped_ptr<base::ListValue>(args->DeepCopy()));
   }
   DispatchEventInternal(profile_, event_name, json_args, args.Pass());
 }