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

webrtc/examples/peerconnection/client/defaults.h

Index: webrtc/examples/peerconnection/client/defaults.h
diff --git a/webrtc/examples/peerconnection/client/defaults.h b/webrtc/examples/peerconnection/client/defaults.h
index 7b503974e505dfea9e5596c3d7dc00e186e353be..f4d3bf52f7d4cc743ef2743e1687752dfc181114 100644
--- a/webrtc/examples/peerconnection/client/defaults.h
+++ b/webrtc/examples/peerconnection/client/defaults.h
@@ -8,8 +8,8 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#ifndef PEERCONNECTION_SAMPLES_CLIENT_DEFAULTS_H_
-#define PEERCONNECTION_SAMPLES_CLIENT_DEFAULTS_H_
+#ifndef WEBRTC_EXAMPLES_PEERCONNECTION_CLIENT_DEFAULTS_H_
+#define WEBRTC_EXAMPLES_PEERCONNECTION_CLIENT_DEFAULTS_H_
 #pragma once
 
 #include <string>
@@ -27,4 +27,4 @@ std::string GetPeerConnectionString();
 std::string GetDefaultServerName();
 std::string GetPeerName();
 
-#endif  // PEERCONNECTION_SAMPLES_CLIENT_DEFAULTS_H_
+#endif  // WEBRTC_EXAMPLES_PEERCONNECTION_CLIENT_DEFAULTS_H_