Cleanup: Fix some lint errors in content/.

content/browser/gamepad/gamepad_test_helpers.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 CONTENT_BROWSER_GAMEPAD_GAMEPAD_TEST_HELPERS_H_
 #define CONTENT_BROWSER_GAMEPAD_GAMEPAD_TEST_HELPERS_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop.h"
 #include "base/synchronization/lock.h"
@@ skipping 51 matching lines @@
 
   scoped_ptr<base::SystemMonitor> system_monitor_;
 
   DISALLOW_COPY_AND_ASSIGN(GamepadTestHelper);
 };
 
 // Constructs a GamepadService with a mock data source. This bypasses the
 // global singleton for the gamepad service.
 class GamepadServiceTestConstructor : public GamepadTestHelper {
  public:
-  GamepadServiceTestConstructor(const WebKit::WebGamepads& test_data);
+  explicit GamepadServiceTestConstructor(const WebKit::WebGamepads& test_data);
   virtual ~GamepadServiceTestConstructor();
 
   GamepadService* gamepad_service() { return gamepad_service_; }
   MockGamepadDataFetcher* data_fetcher() { return data_fetcher_; }
 
  private:
   // Owning pointer (can't be a scoped_ptr due to private destructor).
   GamepadService* gamepad_service_;
 
   // Pointer owned by the provider (which is owned by the gamepad service).
   MockGamepadDataFetcher* data_fetcher_;
 
   DISALLOW_COPY_AND_ASSIGN(GamepadServiceTestConstructor);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_GAMEPAD_GAMEPAD_TEST_HELPERS_H_