Move declaration of stream_type_t up earlier

stream_type_t is used by AudioFlinger class, so it should be declared there.
This way we don't have to peek into PlaybackThread to get the declaration.

Change-Id: Ie08bab1604699214d1e8df2d48d3fbfbbc436e96
diff --git a/services/audioflinger/AudioFlinger.h b/services/audioflinger/AudioFlinger.h
index 97103c4..f80750b 100644
--- a/services/audioflinger/AudioFlinger.h
+++ b/services/audioflinger/AudioFlinger.h
@@ -564,6 +564,18 @@
                     KeyedVector< int, KeyedVector< int, sp<SuspendedSessionDesc> > >  mSuspendedSessions;
     };
 
+    struct  stream_type_t {
+        stream_type_t()
+            :   volume(1.0f),
+                mute(false),
+                valid(true)
+        {
+        }
+        float       volume;
+        bool        mute;
+        bool        valid;
+    };
+
     // --- PlaybackThread ---
     class PlaybackThread : public ThreadBase {
     public:
@@ -758,18 +770,6 @@
 
                             void setStreamValid(audio_stream_type_t streamType, bool valid);
 
-        struct  stream_type_t {
-            stream_type_t()
-                :   volume(1.0f),
-                    mute(false),
-                    valid(true)
-            {
-            }
-            float       volume;
-            bool        mute;
-            bool        valid;
-        };
-
     protected:
         int16_t*                        mMixBuffer;
         int                             mSuspended;
@@ -1412,7 +1412,7 @@
 
 
                 DefaultKeyedVector< audio_io_handle_t, sp<PlaybackThread> >  mPlaybackThreads;
-                PlaybackThread::stream_type_t       mStreamTypes[AUDIO_STREAM_CNT];
+                stream_type_t                       mStreamTypes[AUDIO_STREAM_CNT];
 
                 // both are protected by mLock
                 float                               mMasterVolume;