Fix potential unexpected behavior due to concurrent file writing.

If in future other application use settings intelligence to retrieve Google account profile picture then it is better if app provide Uri, to avoid concurrent file write.

Bug:339351031
Change-Id: Iecd3ae9bf4ff0868667e9cda418fc697eeb5fb75
Test: N/A

core/java/android/content/pm/multiuser.aconfig

@@ -140,6 +140,16 @@ flag {
   }
 }
 
+flag {
+    name: "fix_avatar_concurrent_file_write"
+    namespace: "multiuser"
+    description: "Fix potential unexpected behavior due to concurrent file writing"
+    bug: "339351031"
+    metadata {
+    	purpose: PURPOSE_BUGFIX
+  }
+}
+
 # This flag guards the private space feature and all its implementations excluding the APIs. APIs are guarded by android.os.Flags.allow_private_profile.
 flag {
     name: "enable_private_space_features"