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

chrome/browser/extensions/api/downloads/downloads_api.h

 // 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.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_API_DOWNLOADS_DOWNLOADS_API_H_
 #define CHROME_BROWSER_EXTENSIONS_API_DOWNLOADS_DOWNLOADS_API_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 197 matching lines @@
   FilePath path_;
   scoped_ptr<DownloadFileIconExtractor> icon_extractor_;
   DISALLOW_COPY_AND_ASSIGN(DownloadsGetFileIconFunction);
 };
 
 // Observes a single DownloadManager and many DownloadItems and dispatches
 // onCreated and onErased events.
 class ExtensionDownloadsEventRouter
   : public AllDownloadItemNotifier::Observer {
  public:
-  explicit ExtensionDownloadsEventRouter(
+  ExtensionDownloadsEventRouter(
       Profile* profile, content::DownloadManager* manager);
   virtual ~ExtensionDownloadsEventRouter();
 
   // AllDownloadItemNotifier::Observer interface
   virtual void OnDownloadCreated(
       content::DownloadManager* manager,
       content::DownloadItem* download_item) OVERRIDE;
   virtual void OnDownloadUpdated(
       content::DownloadManager* manager,
       content::DownloadItem* download_item) OVERRIDE;
@@ skipping 10 matching lines @@
  private:
   void DispatchEvent(const char* event_name, base::Value* json_arg);
 
   Profile* profile_;
   AllDownloadItemNotifier notifier_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionDownloadsEventRouter);
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_DOWNLOADS_DOWNLOADS_API_H_