Added first layer of the echo canceller 3 functionality

webrtc/modules/audio_processing/aec3/block_processor.cc

Index: webrtc/modules/audio_processing/aec3/block_processor.cc
diff --git a/webrtc/modules/audio_processing/aec3/block_processor.cc b/webrtc/modules/audio_processing/aec3/block_processor.cc
new file mode 100644
index 0000000000000000000000000000000000000000..3080e54d59a8d299907ea56808dfbdd620031fd1
--- /dev/null
+++ b/webrtc/modules/audio_processing/aec3/block_processor.cc
@@ -0,0 +1,30 @@
+/*
+ *  Copyright (c) 2016 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.
+ */
+#include "webrtc/modules/audio_processing/aec3/block_processor.h"
+
+#include "webrtc/base/optional.h"
+
+namespace webrtc {
+
+BlockProcessor::BlockProcessor(ApmDataDumper* data_dumper,
+                               int sample_rate_hz,
+                               size_t num_bands) {
+  // TODO(peah): Remove once the functionality is added.
+  (void)data_dumper;
+  (void)sample_rate_hz;
+  (void)num_bands;

[ivoc, 2016/12/19 11:30:21]

I'm assuming this is to stop the compiler from complaining about unused
variables? Another way to handle that is to comment out the name of the variable
in the function, i.e.:
BlockProcessor::BlockProcessor(ApmDataDumper* /*data_dumper*/,

[peah-webrtc, 2016/12/20 10:10:24]

Yes, that was the intention. But I now see that it was not needed for these, so
I removed them.

+}
+BlockProcessor::~BlockProcessor() = default;
+
+void BlockProcessor::ProcessCapture(bool known_echo_path_change,
+                                    bool saturated_microphone_signal,
+                                    rtc::ArrayView<float> capture_block) {}
+
+}  // namespace webrtc