liboboe: initial checkin of core and legacy files.

Oboe C++ files that calls AudioTrack and AudioRecord.
Main C API implemented by src/core/OboeAudio.cpp

Test: gunit tests for the Legacy mode and handle tracker in tests folder
Bug: 33347409
Change-Id: I50f9fd99377efbd8de6fef1601e9af4c22c6ab46
Signed-off-by: Phil Burk <philburk@google.com>
diff --git a/media/liboboe/src/utility/MonotonicCounter.h b/media/liboboe/src/utility/MonotonicCounter.h
new file mode 100644
index 0000000..befad21
--- /dev/null
+++ b/media/liboboe/src/utility/MonotonicCounter.h
@@ -0,0 +1,91 @@
+/*
+ * Copyright 2016 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.
+ */
+
+#ifndef UTILITY_MONOTONICCOUNTER_H
+#define UTILITY_MONOTONICCOUNTER_H
+
+#include <stdint.h>
+
+/**
+ * Maintain a 64-bit monotonic counter.
+ * Can be used to track a 32-bit counter that wraps or gets reset.
+ *
+ * Note that this is not atomic and has no interior locks.
+ * A caller will need to provide their own exterior locking
+ * if they need to use it from multiple threads.
+ */
+class MonotonicCounter {
+
+public:
+    MonotonicCounter() {};
+    virtual ~MonotonicCounter() {};
+
+    /**
+     * @return current value of the counter
+     */
+    int64_t get() const {
+        return mCounter64;
+    }
+
+    /**
+     * Advance the counter if delta is positive.
+     * @return current value of the counter
+     */
+    int64_t increment(int64_t delta) {
+        if (delta > 0) {
+            mCounter64 += delta;
+        }
+        return mCounter64;
+    }
+
+    /**
+     * Advance the 64-bit counter if (current32 - previousCurrent32) > 0.
+     * This can be used to convert a 32-bit counter that may be wrapping into
+     * a monotonic 64-bit counter.
+     *
+     * This counter32 should NOT be allowed to advance by more than 0x7FFFFFFF between calls.
+     * Think of the wrapping counter like a sine wave. If the frequency of the signal
+     * is more than half the sampling rate (Nyquist rate) then you cannot measure it properly.
+     * If the counter wraps around every 24 hours then we should measure it with a period
+     * of less than 12 hours.
+     *
+     * @return current value of the 64-bit counter
+     */
+    int64_t update32(int32_t counter32) {
+        int32_t delta = counter32 - mCounter32;
+        // protect against the mCounter64 going backwards
+        if (delta > 0) {
+            mCounter64 += delta;
+            mCounter32 = counter32;
+        }
+        return mCounter64;
+    }
+
+    /**
+     * Reset the stored value of the 32-bit counter.
+     * This is used if your counter32 has been reset to zero.
+     */
+    void reset32() {
+        mCounter32 = 0;
+    }
+
+private:
+    int64_t mCounter64 = 0;
+    int32_t mCounter32 = 0;
+};
+
+
+#endif //UTILITY_MONOTONICCOUNTER_H