Improve volume slider

In the Settings, the Preference#onBindViewHolder will be invoked
3 times when a preference is getting highlighted. This caused that a
disabled volume slider becomes enabled after getting highlighted.

This change is to optimize the init method of VolumeSeekbarPreference
to speed up the initial process and fix the unexpected behavior.

Bug: 275352565
Test: manual test and robotest pass
Change-Id: I77f28386f6d6e4a45297f1ca7bcbaf16ed6136a4

src/com/android/settings/notification/VolumeSeekBarPreference.java

@@ -131,6 +131,11 @@ public class VolumeSeekBarPreference extends SeekBarPreference {
 
     protected void init() {
         if (mSeekBar == null) return;
+        // It's unnecessary to set up relevant volumizer configuration if preference is disabled.
+        if (!isEnabled()) {
+            mSeekBar.setEnabled(false);
+            return;
+        }
         final SeekBarVolumizer.Callback sbvc = new SeekBarVolumizer.Callback() {
             @Override
             public void onSampleStarting(SeekBarVolumizer sbv) {
@@ -179,10 +184,6 @@ public class VolumeSeekBarPreference extends SeekBarPreference {
         if (mListener != null) {
             mListener.onUpdateMuteState();
         }
-        if (!isEnabled()) {
-            mSeekBar.setEnabled(false);
-            mVolumizer.stop();
-        }
     }
 
     protected void updateIconView() {