More style nits.

chrome/browser/extensions/extensions_service.cc

 // Copyright (c) 2009 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/extensions_service.h"
 
 #include "base/command_line.h"
 #include "base/file_util.h"
 #include "base/string_util.h"
 #include "base/values.h"
@@ skipping 18 matching lines @@
 
 #if defined(OS_WIN)
 #include "chrome/browser/extensions/external_registry_extension_provider_win.h"
 #endif
 
 namespace {
 
 // Helper class to collect the IDs of every extension listed in the prefs.
 class InstalledExtensionSet {
  public:
-  InstalledExtensionSet(InstalledExtensions* installed) {
+  explicit InstalledExtensionSet(InstalledExtensions* installed) {
     scoped_ptr<InstalledExtensions> cleanup(installed);
     installed->VisitInstalledExtensions(
         NewCallback(this, &InstalledExtensionSet::ExtensionVisited));
   }
 
   const std::set<std::string>& extensions() { return extensions_; }
 
  private:
   void ExtensionVisited(
       DictionaryValue* manifest, const std::string& id,
@@ skipping 752 matching lines @@
       linked_ptr<ExternalExtensionProvider>(test_provider);
 }
 
 void ExtensionsServiceBackend::OnExternalExtensionFound(
     const std::string& id, const Version* version, const FilePath& path,
     Extension::Location location) {
   frontend_loop_->PostTask(FROM_HERE, NewRunnableMethod(frontend_,
       &ExtensionsService::OnExternalExtensionFound, id, version->GetString(),
       path, location));
 }