Added first layer of the echo canceller 3 functionality

webrtc/modules/audio_processing/aec3/block_processor.h

Index: webrtc/modules/audio_processing/aec3/block_processor.h
diff --git a/webrtc/modules/audio_processing/aec3/block_processor.h b/webrtc/modules/audio_processing/aec3/block_processor.h
new file mode 100644
index 0000000000000000000000000000000000000000..b9c0be19aa969b3c49e3e5393169144d452c7bda
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+++ b/webrtc/modules/audio_processing/aec3/block_processor.h
@@ -0,0 +1,50 @@
+/*
+ *  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.
+ */
+
+#ifndef WEBRTC_MODULES_AUDIO_PROCESSING_AEC3_BLOCK_PROCESSOR_H_
+#define WEBRTC_MODULES_AUDIO_PROCESSING_AEC3_BLOCK_PROCESSOR_H_
+
+#include <memory>
+
+#include "webrtc/base/array_view.h"
+#include "webrtc/base/constructormagic.h"
+#include "webrtc/modules/audio_processing/logging/apm_data_dumper.h"
+
+namespace webrtc {
+
+/* Class for performing echo cancellation on 64 sample blocks of audio data */

[hlundin-webrtc, 2016/12/16 10:04:46]

// style

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

Done.

+class BlockProcessor {
+ public:
+  BlockProcessor(ApmDataDumper* data_dumper,
+                 int sample_rate_hz,
+                 size_t num_bands);
+  ~BlockProcessor();
+
+  /* Processes a block of capture data */

[hlundin-webrtc, 2016/12/16 10:04:46]

// style

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

Done.

+  void ProcessCapture(bool known_echo_path_change,
+                      bool saturated_microphone_signal,
+                      rtc::ArrayView<float> capture_block);
+
+  /* Buffers a block of render data supplied by a FrameBlocker object */

[hlundin-webrtc, 2016/12/16 10:04:46]

// style

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

Done.

+  template <typename F>
+  bool BufferRender(F&& blocker) {

[aleloi, 2016/12/16 15:04:31]

Perhaps change type to std::function<void(ArrayView)> &&, to improve
readability? 

I don't think that the r-value ref is necessary here to avoid copies. If a
temporary is passed by value, I think copy-elision will apply
(http://en.cppreference.com/w/cpp/language/copy_elision, in the call g(f()) no
copy of the f() result is made).

Also, the style guide discourages using r-value refs for other things than
move-assignment, construction and forwarding:
https://google.github.io/styleguide/cppguide.html#Rvalue_references

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

That are definitely valid points! I addressed these, and some of the other
comments, by replacing this approach to instead rely on the swap capabilities of
std::vector.

PTAL

+    // Use blocker to access render data.
+    return true;
+  }
+
+  void ReportEchoLeakage(bool leakage_detected) {}
+
+ private:
+  RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(BlockProcessor);
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_AUDIO_PROCESSING_AEC3_BLOCK_PROCESSOR_H_