Added support in the AEC for refined filter adaptation.

Added support in the AEC for refined filter adaptation.

The following algorithmic functionality was added:
-Add support for an exact regressor power to be computed
 which avoids the issue with the updating of the filter
 sometimes being unstable.
-Lowered the fixed step size of the adaptive filter to 0.05
 which significantly reduces the sensitivity of the
 adaptive filter to near-end noise, nonlinearities,
 doubletalk and the unmodelled echo path tail. It also
 reduces the tracking speed of the adaptive filter but the
 chosen value proved to give a sufficient tradeoff for the
 requirements on the adaptive filter.

To allow the new functionality to be selectively applied the following was done:
-A new Config was added for selectively activating the functionality.
-Functionality was added in the audioprocessing  and echocancellationimpl classes
 for passing the activation of the functionality down to the AEC algorithms.

To make the code for the introduction of the functionality clean,
the following refactoring was done:
-The selection of the step size was moved to a single place.
-The constant for the step size of the adaptive filter in extended filter mode was
 made local.
-The state variable storing the step-size was renamed to a more describing name.

When the new functionality is not activated, the changes
have been tested for bitexactness on Linux.

TBR=minyue@webrtc.org
BUG=webrtc:5778, webrtc:5777, 603411
Review URL: https://codereview.webrtc.org/1887003002

Cr-Commit-Position: refs/heads/master@{#12384}
(cherry picked from commit 0332c2db39d6f5c780ce9e92b850bcb57e24e7f8)

Committed: https://chromium.googlesource.com/external/webrtc/+/ffdb392cfb40af4c2258704aaba2d46c3d70f4b6

[hlundin-webrtc, 2016-04-28 19:18:25]

Description was changed from

==========
Added support in the AEC for refined filter adaptation.

The following algorithmic functionality was added:
-Add support for an exact regressor power to be computed
 which avoids the issue with the updating of the filter
 sometimes being unstable.
-Lowered the fixed step size of the adaptive filter to 0.05
 which significantly reduces the sensitivity of the
 adaptive filter to near-end noise, nonlinearities,
 doubletalk and the unmodelled echo path tail. It also
 reduces the tracking speed of the adaptive filter but the
 chosen value proved to give a sufficient tradeoff for the
 requirements on the adaptive filter.

To allow the new functionality to be selectively applied the following was done:
-A new Config was added for selectively activating the functionality.
-Functionality was added in the audioprocessing  and echocancellationimpl
classes
 for passing the activation of the functionality down to the AEC algorithms.

To make the code for the introduction of the functionality clean,
the following refactoring was done:
-The selection of the step size was moved to a single place.
-The constant for the step size of the adaptive filter in extended filter mode
was
 made local.
-The state variable storing the step-size was renamed to a more describing name.

When the new functionality is not activated, the changes
have been tested for bitexactness on Linux.

TBR=minyue@webrtc.org
BUG=webrtc:5778, webrtc:5777, 603411

Review URL: https://codereview.webrtc.org/1887003002

Cr-Commit-Position: refs/heads/master@{#12384}
(cherry picked from commit 0332c2db39d6f5c780ce9e92b850bcb57e24e7f8)
==========

to

==========
Added support in the AEC for refined filter adaptation.

The following algorithmic functionality was added:
-Add support for an exact regressor power to be computed
 which avoids the issue with the updating of the filter
 sometimes being unstable.
-Lowered the fixed step size of the adaptive filter to 0.05
 which significantly reduces the sensitivity of the
 adaptive filter to near-end noise, nonlinearities,
 doubletalk and the unmodelled echo path tail. It also
 reduces the tracking speed of the adaptive filter but the
 chosen value proved to give a sufficient tradeoff for the
 requirements on the adaptive filter.

To allow the new functionality to be selectively applied the following was done:
-A new Config was added for selectively activating the functionality.
-Functionality was added in the audioprocessing  and echocancellationimpl
classes
 for passing the activation of the functionality down to the AEC algorithms.

To make the code for the introduction of the functionality clean,
the following refactoring was done:
-The selection of the step size was moved to a single place.
-The constant for the step size of the adaptive filter in extended filter mode
was
 made local.
-The state variable storing the step-size was renamed to a more describing name.

When the new functionality is not activated, the changes
have been tested for bitexactness on Linux.

TBR=minyue@webrtc.org
BUG=webrtc:5778, webrtc:5777, 603411

Review URL: https://codereview.webrtc.org/1887003002

Cr-Commit-Position: refs/heads/master@{#12384}
(cherry picked from commit 0332c2db39d6f5c780ce9e92b850bcb57e24e7f8)

Committed:
https://chromium.googlesource.com/external/webrtc/+/ffdb392cfb40af4c2258704aa...
==========

[hlundin-webrtc, 2016-04-28 19:18:26]

Committed patchset #1 (id:1) manually as
ffdb392cfb40af4c2258704aaba2d46c3d70f4b6.