Add a Config class interface to AudioProcessing for passing options.

Pass the Config down to all AudioProcessing components.

Also add an EchoCancellationImplWrapper to optionally create different
EchoCancellationImpls.

BUG=2117
TBR=turaj@webrtc.org
TESTED=git try

Review URL: https://webrtc-codereview.appspot.com/1843004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@4400 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/audio_processing/include/mock_audio_processing.h

@@ -181,6 +181,8 @@ class MockAudioProcessing : public AudioProcessing {
 
   MOCK_METHOD0(Initialize,
       int());
+  MOCK_METHOD1(SetExtraOptions,
+      void(const Config& config));
   MOCK_METHOD1(set_sample_rate_hz,
       int(int rate));
   MOCK_CONST_METHOD0(sample_rate_hz,