Handle remaining hidden API usages

There are several hidden API usages from Media 1.0 APIs.
To move Media 1.0 APIs into mainline module, this CL removes
the unnecesarry usages or makes them as system APIs.

Bug: 119539695
Test: pass MediaSessionTest and MediaControllerTest, and
      manually check whether SystemUI can control sessions.
Change-Id: I824113229964ad9b5785ecd488b5851b0dace626

api/system-current.txt

@@ -3389,6 +3389,15 @@ package android.media {
     method @NonNull public android.media.TimedMetaData.Builder setTimedMetaData(long, @NonNull byte[]);
   }
 
+  public abstract class VolumeProvider {
+    method public void setCallback(android.media.VolumeProvider.Callback);
+  }
+
+  public abstract static class VolumeProvider.Callback {
+    ctor public VolumeProvider.Callback();
+    method public abstract void onVolumeChanged(android.media.VolumeProvider);
+  }
+
 }
 
 package android.media.audiopolicy {
@@ -3564,6 +3573,10 @@ package android.media.session {
     method public void onSetMediaButtonEventDelegate(@NonNull android.media.session.MediaSessionEngine.MediaButtonEventDelegate);
   }
 
+  public static final class MediaSession.Token implements android.os.Parcelable {
+    method public android.media.session.ControllerLink getControllerLink();
+  }
+
   public final class MediaSessionEngine implements java.lang.AutoCloseable {
     ctor public MediaSessionEngine(@NonNull android.content.Context, @NonNull android.media.session.SessionLink, @NonNull android.media.session.SessionCallbackLink, @NonNull android.media.session.MediaSessionEngine.CallbackStub, int);
     method public void close();

media/java/android/media/VolumeProvider.java

@@ -16,6 +16,7 @@
 package android.media;
 
 import android.annotation.IntDef;
+import android.annotation.SystemApi;
 import android.media.session.MediaSession;
 
 import java.lang.annotation.Retention;
@@ -147,6 +148,7 @@ public abstract class VolumeProvider {
      * Sets a callback to receive volume changes.
      * @hide
      */
+    @SystemApi
     public void setCallback(Callback callback) {
         mCallback = callback;
     }
@@ -155,6 +157,7 @@ public abstract class VolumeProvider {
      * Listens for changes to the volume.
      * @hide
      */
+    @SystemApi
     public static abstract class Callback {
         public abstract void onVolumeChanged(VolumeProvider volumeProvider);
     }

media/java/android/media/session/ControllerCallbackLink.java

@@ -315,12 +315,6 @@ public final class ControllerCallbackLink implements Parcelable {
         }
 
         private void ensureMediaControlPermission() {
-            // Allow API calls from the System UI
-            if (mContext.checkCallingPermission(android.Manifest.permission.STATUS_BAR_SERVICE)
-                    == PackageManager.PERMISSION_GRANTED) {
-                return;
-            }
-
             // Check if it's system server or has MEDIA_CONTENT_CONTROL.
             // Note that system server doesn't have MEDIA_CONTENT_CONTROL, so we need extra
             // check here.

media/java/android/media/session/MediaSession.java

@@ -481,7 +481,7 @@ public final class MediaSession {
          * @hide
          */
         @SystemApi
-        ControllerLink getControllerLink() {
+        public ControllerLink getControllerLink() {
             return mControllerLink;
         }
 

media/java/android/media/session/SessionCallbackLink.java

@@ -944,12 +944,6 @@ public final class SessionCallbackLink implements Parcelable {
         }
 
         private void ensureMediaControlPermission() {
-            // Allow API calls from the System UI
-            if (mContext.checkCallingPermission(android.Manifest.permission.STATUS_BAR_SERVICE)
-                    == PackageManager.PERMISSION_GRANTED) {
-                return;
-            }
-
             // Check if it's system server or has MEDIA_CONTENT_CONTROL.
             // Note that system server doesn't have MEDIA_CONTENT_CONTROL, so we need extra
             // check here.