Revert "Make MmsManager public"

This reverts commit 0339a82c0a2772c200aa29867746391cb5af0e8b.

Reason for revert: RP1A.200110.001 cannot send/receive MMS

Bug: 147475284
Change-Id: I5952168aba996a10554406a9f1675ac3b04fa41f
diff --git a/mms/java/android/telephony/MmsManager.java b/mms/java/android/telephony/MmsManager.java
index 24ea3cf..6554267 100644
--- a/mms/java/android/telephony/MmsManager.java
+++ b/mms/java/android/telephony/MmsManager.java
@@ -16,11 +16,8 @@
 
 package android.telephony;
 
-import android.annotation.NonNull;
-import android.annotation.Nullable;
 import android.app.ActivityThread;
 import android.app.PendingIntent;
-import android.content.Context;
 import android.net.Uri;
 import android.os.Bundle;
 import android.os.RemoteException;
@@ -30,16 +27,22 @@
 
 /**
  * Manages MMS operations such as sending multimedia messages.
+ * Get this object by calling the static method {@link #getInstance()}.
+ * @hide
  */
-public final class MmsManager {
+public class MmsManager {
     private static final String TAG = "MmsManager";
-    private final Context mContext;
+
+    /** Singleton object constructed during class initialization. */
+    private static final MmsManager sInstance = new MmsManager();
 
     /**
-     * @hide
+     * Get the MmsManager singleton instance.
+     *
+     * @return the {@link MmsManager} singleton instance.
      */
-    public MmsManager(@NonNull Context context) {
-        mContext = context;
+    public static MmsManager getInstance() {
+        return sInstance;
     }
 
     /**
@@ -53,9 +56,8 @@
      * @param sentIntent if not NULL this <code>PendingIntent</code> is broadcast when the message
      *                   is successfully sent, or failed
      */
-    public void sendMultimediaMessage(int subId, @NonNull Uri contentUri,
-            @Nullable String locationUrl, @Nullable Bundle configOverrides,
-            @Nullable PendingIntent sentIntent) {
+    public void sendMultimediaMessage(int subId, Uri contentUri, String locationUrl,
+            Bundle configOverrides, PendingIntent sentIntent) {
         try {
             final IMms iMms = IMms.Stub.asInterface(ServiceManager.getService("imms"));
             if (iMms == null) {
@@ -82,9 +84,8 @@
      *  broadcast when the message is downloaded, or the download is failed
      * @throws IllegalArgumentException if locationUrl or contentUri is empty
      */
-    public void downloadMultimediaMessage(int subId, @NonNull String locationUrl,
-            @NonNull Uri contentUri, @Nullable Bundle configOverrides,
-            @Nullable PendingIntent downloadedIntent) {
+    public void downloadMultimediaMessage(int subId, String locationUrl, Uri contentUri,
+            Bundle configOverrides, PendingIntent downloadedIntent) {
         try {
             final IMms iMms = IMms.Stub.asInterface(ServiceManager.getService("imms"));
             if (iMms == null) {