Add VTS test for NFC observe mode

Test: this is only a test; manual run on a device
Bug: 305979303 326470047
Change-Id: Idf4953e942bb5db8c2ee72779dfdf80ed4e224b2
diff --git a/nfc/aidl/vts/functional/SyncEvent.h b/nfc/aidl/vts/functional/SyncEvent.h
new file mode 100644
index 0000000..352a549
--- /dev/null
+++ b/nfc/aidl/vts/functional/SyncEvent.h
@@ -0,0 +1,143 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ *  Synchronize two or more threads using a condition variable and a mutex.
+ */
+#pragma once
+#include <mutex>
+
+#include "CondVar.h"
+
+class SyncEvent {
+  public:
+    /*******************************************************************************
+    **
+    ** Function:        ~SyncEvent
+    **
+    ** Description:     Cleanup all resources.
+    **
+    ** Returns:         None.
+    **
+    *******************************************************************************/
+    ~SyncEvent() {}
+
+    /*******************************************************************************
+    **
+    ** Function:        start
+    **
+    ** Description:     Start a synchronization operation.
+    **
+    ** Returns:         None.
+    **
+    *******************************************************************************/
+    void start() { mMutex.lock(); }
+
+    /*******************************************************************************
+    **
+    ** Function:        wait
+    **
+    ** Description:     Block the thread and wait for the event to occur.
+    **
+    ** Returns:         None.
+    **
+    *******************************************************************************/
+    void wait() { mCondVar.wait(mMutex); }
+
+    /*******************************************************************************
+    **
+    ** Function:        wait
+    **
+    ** Description:     Block the thread and wait for the event to occur.
+    **                  millisec: Timeout in milliseconds.
+    **
+    ** Returns:         True if wait is successful; false if timeout occurs.
+    **
+    *******************************************************************************/
+    bool wait(long millisec) {
+        bool retVal = mCondVar.wait(mMutex, millisec);
+        return retVal;
+    }
+
+    /*******************************************************************************
+    **
+    ** Function:        notifyOne
+    **
+    ** Description:     Notify a blocked thread that the event has occurred.
+    *Unblocks it.
+    **
+    ** Returns:         None.
+    **
+    *******************************************************************************/
+    void notifyOne() { mCondVar.notifyOne(); }
+
+    /*******************************************************************************
+    **
+    ** Function:        end
+    **
+    ** Description:     End a synchronization operation.
+    **
+    ** Returns:         None.
+    **
+    *******************************************************************************/
+    void end() { mMutex.unlock(); }
+
+  private:
+    CondVar mCondVar;
+    std::mutex mMutex;
+};
+
+/*****************************************************************************/
+/*****************************************************************************/
+
+/*****************************************************************************
+**
+**  Name:           SyncEventGuard
+**
+**  Description:    Automatically start and end a synchronization event.
+**
+*****************************************************************************/
+class SyncEventGuard {
+  public:
+    /*******************************************************************************
+    **
+    ** Function:        SyncEventGuard
+    **
+    ** Description:     Start a synchronization operation.
+    **
+    ** Returns:         None.
+    **
+    *******************************************************************************/
+    SyncEventGuard(SyncEvent& event) : mEvent(event) {
+        event.start();  // automatically start operation
+    };
+
+    /*******************************************************************************
+    **
+    ** Function:        ~SyncEventGuard
+    **
+    ** Description:     End a synchronization operation.
+    **
+    ** Returns:         None.
+    **
+    *******************************************************************************/
+    ~SyncEventGuard() {
+        mEvent.end();  // automatically end operation
+    };
+
+  private:
+    SyncEvent& mEvent;
+};