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

chrome/browser/sessions/session_service_test_helper.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_SESSIONS_SESSION_SERVICE_TEST_HELPER_H_
 #define CHROME_BROWSER_SESSIONS_SESSION_SERVICE_TEST_HELPER_H_
 
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "chrome/browser/sessions/session_id.h"
 
 class SessionBackend;
 class SessionCommand;
 class SessionService;
 struct SessionTab;
 struct SessionWindow;
 class TabNavigation;
 
 // A simple class that makes writing SessionService related tests easier.
 
 class SessionServiceTestHelper {
  public:
-  explicit SessionServiceTestHelper();
+  SessionServiceTestHelper();
   explicit SessionServiceTestHelper(SessionService* service);
   ~SessionServiceTestHelper();
 
   void PrepareTabInWindow(const SessionID& window_id,
                           const SessionID& tab_id,
                           int visual_index,
                           bool select);
 
   void SetTabExtensionAppID(const SessionID& window_id,
                             const SessionID& tab_id,
@@ skipping 35 matching lines @@
 
   SessionBackend* backend();
 
  private:
   scoped_ptr<SessionService> service_;
 
   DISALLOW_COPY_AND_ASSIGN(SessionServiceTestHelper);
 };
 
 #endif  // CHROME_BROWSER_SESSIONS_SESSION_SERVICE_TEST_HELPER_H_