Remove legacy weirdness in Merge::Downsample

In practice, this will have only marginal effect. The length_limit
was increased from 6.7 ms to 10 ms. This is compared with the
input_length, which is equal to the decoded frame size. Thus,
this change will only affect encoded frame sizes in this range
(including 10 ms).

BUG=2696
R=tina.legrand@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/9969004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@5700 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/webrtc/modules/audio_coding/neteq4/merge.cc b/webrtc/modules/audio_coding/neteq4/merge.cc
index 463b2ca..4b56016 100644
--- a/webrtc/modules/audio_coding/neteq4/merge.cc
+++ b/webrtc/modules/audio_coding/neteq4/merge.cc
@@ -248,7 +248,7 @@
   int num_coefficients;
   int decimation_factor = fs_hz_ / 4000;
   static const int kCompensateDelay = 0;
-  int length_limit = fs_hz_ / 100;
+  int length_limit = fs_hz_ / 100;  // 10 ms in samples.
   if (fs_hz_ == 8000) {
     filter_coefficients = DspHelper::kDownsample8kHzTbl;
     num_coefficients = 3;
@@ -261,8 +261,6 @@
   } else {  // fs_hz_ == 48000
     filter_coefficients = DspHelper::kDownsample48kHzTbl;
     num_coefficients = 7;
-    // TODO(hlundin) Why is |length_limit| not 480 (legacy)?
-    length_limit = 320;
   }
   int signal_offset = num_coefficients - 1;
   WebRtcSpl_DownsampleFast(&expanded_signal[signal_offset],