Use uint32_t for sample rate

Change-Id: Ie240b48fb54b08359f69ecd4e5f8bda3d15cbe80
diff --git a/include/media/AudioTrack.h b/include/media/AudioTrack.h
index b82f814..99d583d 100644
--- a/include/media/AudioTrack.h
+++ b/include/media/AudioTrack.h
@@ -282,7 +282,9 @@
 
     /* Set sample rate for this track in Hz, mostly used for games' sound effects
      */
-            status_t    setSampleRate(int sampleRate);
+            status_t    setSampleRate(uint32_t sampleRate);
+
+    /* Return current sample rate in Hz, or 0 if unknown */
             uint32_t    getSampleRate() const;
 
     /* Enables looping and sets the start and end points of looping.