Split MoveReadPosition into Forward and Backward versions.

webrtc/common_audio/audio_ring_buffer_unittest.cc

Index: webrtc/common_audio/audio_ring_buffer_unittest.cc
diff --git a/webrtc/common_audio/audio_ring_buffer_unittest.cc b/webrtc/common_audio/audio_ring_buffer_unittest.cc
index 65d7136de1aeeae05fd76b0136daa87fa3bc03b8..a83c87599c414c127e95881e88873d4100ff237b 100644
--- a/webrtc/common_audio/audio_ring_buffer_unittest.cc
+++ b/webrtc/common_audio/audio_ring_buffer_unittest.cc
@@ -98,11 +98,11 @@ TEST_F(AudioRingBufferTest, MoveReadPosition) {
   AudioRingBuffer buf(kNumChannels, kNumFrames);
   buf.Write(input.channels(), kNumChannels, kNumFrames);
 
-  buf.MoveReadPosition(3);
+  buf.MoveReadPositionForward(3);
   ChannelBuffer<float> output(1, kNumChannels);
   buf.Read(output.channels(), kNumChannels, 1);
   EXPECT_EQ(4, output.channels()[0][0]);
-  buf.MoveReadPosition(-3);
+  buf.MoveReadPositionBackward(3);
   buf.Read(output.channels(), kNumChannels, 1);
   EXPECT_EQ(2, output.channels()[0][0]);
 }