NetEq4: Make some DSP operation classes member variables

This CL reduces the memory allocations by making the instances of
Accelerate, PreemptiveExpand, Normal and Merge member variables in
NetEqImpl.

This change reduced the allocation count by 20,000 in the bit-exactness
test.

BUG=Issue 1363
TEST=out/Debug/modules_unittests
--gtest_filter=NetEqDecodingTest.TestBitExactness

R=andrew@webrtc.org, minyue@webrtc.org, turaj@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/2158004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@4776 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/webrtc/modules/audio_coding/neteq4/neteq_impl.h b/webrtc/modules/audio_coding/neteq4/neteq_impl.h
index 9bdafdd..d504a11 100644
--- a/webrtc/modules/audio_coding/neteq4/neteq_impl.h
+++ b/webrtc/modules/audio_coding/neteq4/neteq_impl.h
@@ -27,6 +27,7 @@
 namespace webrtc {
 
 // Forward declarations.
+class Accelerate;
 class BackgroundNoise;
 class BufferLevelFilter;
 class ComfortNoise;
@@ -38,9 +39,12 @@
 class DtmfBuffer;
 class DtmfToneGenerator;
 class Expand;
+class Merge;
+class Normal;
 class PacketBuffer;
 class PayloadSplitter;
 class PostDecodeVad;
+class PreemptiveExpand;
 class RandomVector;
 class SyncBuffer;
 class TimestampScaler;
@@ -299,6 +303,10 @@
   AudioMultiVector<int16_t>* algorithm_buffer_;
   SyncBuffer* sync_buffer_;
   Expand* expand_;
+  scoped_ptr<Normal> normal_;
+  scoped_ptr<Merge> merge_;
+  scoped_ptr<Accelerate> accelerate_;
+  scoped_ptr<PreemptiveExpand> preemptive_expand_;
   RandomVector random_vector_;
   ComfortNoise* comfort_noise_;
   Rtcp rtcp_;