"Disallow adjust volume" restricted dialog didn't show

root casue: VolumeSeekBarPreference & SeekBarPreference will return
false when call isSelectable() then this preference won't perform Click

Fixes: 123745455
Test: Manual & robotest
Change-Id: Iba27b503e8a272260c80bd41aecdd5cdbc39f962

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

@@ -80,11 +80,6 @@ public class VolumeSeekBarPreference extends SeekBarPreference {
         mAudioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
     }
 
-    @Override
-    public boolean isSelectable() {
-        return false;
-    }
-
     public void setStream(int stream) {
         mStream = stream;
         setMax(mAudioManager.getStreamMaxVolume(mStream));

src/com/android/settings/widget/SeekBarPreference.java

@@ -93,7 +93,7 @@ public class SeekBarPreference extends RestrictedPreference
 
     @Override
     public boolean isSelectable() {
-        return false;
+        return isDisabledByAdmin();
     }
 
     @Override

tests/robotests/src/com/android/settings/widget/SeekBarPreferenceTest.java

@@ -18,12 +18,16 @@ package com.android.settings.widget;
 
 import static com.google.common.truth.Truth.assertThat;
 
+import static org.mockito.Mockito.spy;
+import static org.mockito.Mockito.when;
+
 import android.content.Context;
 import android.os.Parcelable;
 
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
+import org.mockito.MockitoAnnotations;
 import org.robolectric.RobolectricTestRunner;
 import org.robolectric.RuntimeEnvironment;
 
@@ -39,9 +43,10 @@ public class SeekBarPreferenceTest {
 
     @Before
     public void setUp() {
+        MockitoAnnotations.initMocks(this);
         mContext = RuntimeEnvironment.application;
 
-        mSeekBarPreference = new SeekBarPreference(mContext);
+        mSeekBarPreference = spy(new SeekBarPreference(mContext));
         mSeekBarPreference.setMax(MAX);
         mSeekBarPreference.setMin(MIN);
         mSeekBarPreference.setProgress(PROGRESS);
@@ -59,4 +64,18 @@ public class SeekBarPreferenceTest {
         assertThat(preference.getMin()).isEqualTo(MIN);
         assertThat(preference.getProgress()).isEqualTo(PROGRESS);
     }
+
+    @Test
+    public void isSelectable_disabledByAdmin_returnTrue() {
+        when(mSeekBarPreference.isDisabledByAdmin()).thenReturn(true);
+
+        assertThat(mSeekBarPreference.isSelectable()).isTrue();
+    }
+
+    @Test
+    public void isSelectable_notDisabledByAdmin_returnFalse() {
+        when(mSeekBarPreference.isDisabledByAdmin()).thenReturn(false);
+
+        assertThat(mSeekBarPreference.isSelectable()).isFalse();
+    }
 }