AudioTrack::mute() is unused so remove it

If ever needed again, it could be implemented on client side by forcing
a track volume of 0.

Change-Id: I88a9b4f675b6dca2948549414f9ec2c192d29269
diff --git a/media/libmedia/AudioTrack.cpp b/media/libmedia/AudioTrack.cpp
index 0463433..f5641e0 100644
--- a/media/libmedia/AudioTrack.cpp
+++ b/media/libmedia/AudioTrack.cpp
@@ -304,7 +304,6 @@
     }
 
     mSharedBuffer = sharedBuffer;
-    mMuted = false;
     mActive = false;
     mUserData = user;
     mLoopCount = 0;
@@ -453,12 +452,6 @@
     }
 }
 
-void AudioTrack::mute(bool e)
-{
-    mAudioTrack->mute(e);
-    mMuted = e;
-}
-
 status_t AudioTrack::setVolume(float left, float right)
 {
     if (left < 0.0f || left > 1.0f || right < 0.0f || right > 1.0f) {
@@ -1424,8 +1417,8 @@
     snprintf(buffer, 255, "  format(%d), channel count(%d), frame count(%d)\n", mFormat,
             mChannelCount, mFrameCount);
     result.append(buffer);
-    snprintf(buffer, 255, "  sample rate(%u), status(%d), muted(%d)\n",
-            (cblk == 0) ? 0 : cblk->sampleRate, mStatus, mMuted);
+    snprintf(buffer, 255, "  sample rate(%u), status(%d)\n",
+            (cblk == 0) ? 0 : cblk->sampleRate, mStatus);
     result.append(buffer);
     snprintf(buffer, 255, "  active(%d), latency (%d)\n", mActive, mLatency);
     result.append(buffer);