Adding second layer of the echo canceller 3 functionality.

webrtc/modules/audio_processing/test/echo_canceller_test_tools.cc

+/*
+ *  Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.

[hlundin-webrtc, 2017/01/18 13:08:51]

2017

[peah-webrtc, 2017/01/19 15:33:07]

Done.

+ *
+ *  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.
+ */
+
+#include "webrtc/modules/audio_processing/test/echo_canceller_test_tools.h"
+
+#include "webrtc/base/checks.h"
+
+namespace webrtc {
+
+void RandomizeSampleVector(Random* random_generator, rtc::ArrayView<float> v) {
+  for (auto& v_k : v) {
+    v_k = 2 * 32767.f * random_generator->Rand<float>() - 32767.f;
+  }
+}
+
+}  // namespace webrtc