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

chrome/common/extensions/extension.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_COMMON_EXTENSIONS_EXTENSION_H_
 #define CHROME_COMMON_EXTENSIONS_EXTENSION_H_
 
 #include <algorithm>
 #include <iosfwd>
 #include <map>
@@ skipping 180 matching lines @@
     OAuth2Info();
     ~OAuth2Info();
 
     OAuth2Scopes GetScopesAsSet();
 
     std::string client_id;
     std::vector<std::string> scopes;
   };
 
   struct ActionInfo {
-    explicit ActionInfo();
+    ActionInfo();
     ~ActionInfo();
 
     // The types of extension actions.
     enum Type {
       TYPE_BROWSER,
       TYPE_PAGE,
       TYPE_SCRIPT_BADGE,
       TYPE_SYSTEM_INDICATOR,
     };
 
     // Empty implies the key wasn't present.
     ExtensionIconSet default_icon;
     std::string default_title;
     GURL default_popup_url;
     // action id -- only used with legacy page actions API.
     std::string id;
   };
 
   struct FileHandlerInfo {
-    explicit FileHandlerInfo();
+    FileHandlerInfo();
     ~FileHandlerInfo();
     std::string id;
     std::string title;
 
     // File extensions associated with this handler.
     std::set<std::string> extensions;
 
     // MIME types associated with this handler.
     std::set<std::string> types;
   };
@@ skipping 1051 matching lines @@
 
   UpdatedExtensionPermissionsInfo(
       const Extension* extension,
       const PermissionSet* permissions,
       Reason reason);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_COMMON_EXTENSIONS_EXTENSION_H_