Do not call retrieveMedia() if it is already done

Bug: 77304533
Test: succeeded building and tested aosp Music app with 60 mp3 files.
Change-Id: I69cdef1f11cf36502dffd0be41d62711adfd49d4
diff --git a/src/com/android/music/utils/MusicProvider.java b/src/com/android/music/utils/MusicProvider.java
index bda92ea..d60b585 100644
--- a/src/com/android/music/utils/MusicProvider.java
+++ b/src/com/android/music/utils/MusicProvider.java
@@ -225,6 +225,9 @@
         new AsyncTask<Void, Void, State>() {
             @Override
             protected State doInBackground(Void... params) {
+                if (mCurrentState == State.INITIALIZED) {
+                    return mCurrentState;
+                }
                 mCurrentState = State.INITIALIZING;
                 if (retrieveMedia()) {
                     mCurrentState = State.INITIALIZED;
@@ -477,4 +480,4 @@
             //            buildListsByGenre();
         }
     }
-}
\ No newline at end of file
+}