Support for Signal calls.

Merge in RedPhone

// FREEBIE

jni/webrtc/system_wrappers/source/critical_section_posix.h

@@ -0,0 +1,36 @@
+/*
+ *  Copyright (c) 2011 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 WEBRTC_SYSTEM_WRAPPERS_SOURCE_CRITICAL_SECTION_POSIX_H_
+#define WEBRTC_SYSTEM_WRAPPERS_SOURCE_CRITICAL_SECTION_POSIX_H_
+
+#include "webrtc/system_wrappers/interface/critical_section_wrapper.h"
+
+#include <pthread.h>
+
+namespace webrtc {
+
+class CriticalSectionPosix : public CriticalSectionWrapper {
+ public:
+  CriticalSectionPosix();
+
+  virtual ~CriticalSectionPosix();
+
+  virtual void Enter() OVERRIDE;
+  virtual void Leave() OVERRIDE;
+
+ private:
+  pthread_mutex_t mutex_;
+  friend class ConditionVariablePosix;
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_SYSTEM_WRAPPERS_SOURCE_CRITICAL_SECTION_POSIX_H_