Add all-channel AudioTrack::setVolume() API

Add combined channel APIs setVolume to AudioTrack,
and remove obsolete getVolume.

Change-Id: I0c87bfdbff4f4292259fa33e65f67badbafd270b
diff --git a/media/libmedia/AudioTrack.cpp b/media/libmedia/AudioTrack.cpp
index ffed161..596523d 100644
--- a/media/libmedia/AudioTrack.cpp
+++ b/media/libmedia/AudioTrack.cpp
@@ -529,14 +529,9 @@
     return NO_ERROR;
 }
 
-void AudioTrack::getVolume(float* left, float* right) const
+status_t AudioTrack::setVolume(float volume)
 {
-    if (left != NULL) {
-        *left  = mVolume[LEFT];
-    }
-    if (right != NULL) {
-        *right = mVolume[RIGHT];
-    }
+    return setVolume(volume, volume);
 }
 
 status_t AudioTrack::setAuxEffectSendLevel(float level)
diff --git a/media/libmedia/ToneGenerator.cpp b/media/libmedia/ToneGenerator.cpp
index 253602d..42584fe 100644
--- a/media/libmedia/ToneGenerator.cpp
+++ b/media/libmedia/ToneGenerator.cpp
@@ -1036,7 +1036,7 @@
         goto initAudioTrack_exit;
     }
 
-    mpAudioTrack->setVolume(mVolume, mVolume);
+    mpAudioTrack->setVolume(mVolume);
 
     mState = TONE_INIT;