Move one CircularBuffer to webrtc::test namespace.

There are currently two webrtc::CircularBuffers defined:
- modules/audio_coding/test/utility.{h,cc}
- modules/audio_processing/echo_detector/circular_buffer.{h,cc}

This CL moves the former definition to the webrtc::test namespace,
to avoid link errors in a future build target.

BUG=None

Review-Url: https://codereview.webrtc.org/2667383008
Cr-Commit-Position: refs/heads/master@{#16553}

webrtc/modules/audio_coding/test/APITest.cc

@@ -678,7 +678,7 @@ void APITest::TestDelay(char side) {
   double averageEstimDelay = 0;
   double averageDelay = 0;
 
-  CircularBuffer estimDelayCB(100);
+  test::CircularBuffer estimDelayCB(100);
   estimDelayCB.SetArithMean(true);
 
   if (side == 'A') {

webrtc/modules/audio_coding/test/utility.cc

@@ -136,6 +136,8 @@ void PrintCodecs() {
 
 }
 
+namespace test {
+
 CircularBuffer::CircularBuffer(uint32_t len)
     : _buff(NULL),
       _idx(0),
@@ -265,6 +267,8 @@ int16_t CircularBuffer::Variance(double& var) {
   }
 }
 
+}  // namespace test
+
 bool FixedPayloadTypeCodec(const char* payloadName) {
   char fixPayloadTypeCodecs[NUM_CODECS_WITH_FIXED_PAYLOAD_TYPE][32] = { "PCMU",
       "PCMA", "GSM", "G723", "DVI4", "LPC", "PCMA", "G722", "QCELP", "CN",

webrtc/modules/audio_coding/test/utility.h

@@ -83,6 +83,9 @@ class ACMTestTimer {
   unsigned long _hour;
 };
 
+// To avoid clashes with CircularBuffer in APM.
+namespace test {
+
 class CircularBuffer {
  public:
   CircularBuffer(uint32_t len);
@@ -109,6 +112,8 @@ class CircularBuffer {
   double _sumSqr;
 };
 
+}  // namespace test
+
 int16_t ChooseCodec(CodecInst& codecInst);
 
 void PrintCodecs();