Enable cpplint for webrtc/examples and fix all uncovered cpplint errors.

webrtc/examples/peerconnection/client/linux/main_wnd.h

 /*
  *  Copyright 2012 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#ifndef PEERCONNECTION_SAMPLES_CLIENT_LINUX_MAIN_WND_H_
-#define PEERCONNECTION_SAMPLES_CLIENT_LINUX_MAIN_WND_H_
+#ifndef WEBRTC_EXAMPLES_PEERCONNECTION_CLIENT_LINUX_MAIN_WND_H_
+#define WEBRTC_EXAMPLES_PEERCONNECTION_CLIENT_LINUX_MAIN_WND_H_
+
+#include <string>
 
 #include "webrtc/examples/peerconnection/client/main_wnd.h"
 #include "webrtc/examples/peerconnection/client/peer_connection_client.h"
 
 // Forward declarations.
 typedef struct _GtkWidget GtkWidget;
 typedef union _GdkEvent GdkEvent;
 typedef struct _GdkEventKey GdkEventKey;
 typedef struct _GtkTreeView GtkTreeView;
 typedef struct _GtkTreePath GtkTreePath;
@@ skipping 85 matching lines @@
   std::string server_;
   std::string port_;
   bool autoconnect_;
   bool autocall_;
   rtc::scoped_ptr<VideoRenderer> local_renderer_;
   rtc::scoped_ptr<VideoRenderer> remote_renderer_;
   rtc::scoped_ptr<uint8_t[]> draw_buffer_;
   int draw_buffer_size_;
 };
 
-#endif  // PEERCONNECTION_SAMPLES_CLIENT_LINUX_MAIN_WND_H_
+#endif  // WEBRTC_EXAMPLES_PEERCONNECTION_CLIENT_LINUX_MAIN_WND_H_