Channel settings updates

- Update master switch preference to store enabled state in case
it's set before the view holder is bound
- Update master switch preference to prevent disabled switches
from being toggled
- Show an importance summary for max importance
- properly handle null notification sounds

Change-Id: I395b95b76d2a3c1c94b41d1c2720bb0cf1cae917
Fixes: 36920159
Fixes: 37421928
Fixes: 36939825
Test: RunSettingsRoboTests & manual

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

@@ -90,6 +90,19 @@ public class MasterSwitchPreferenceTest {
         assertThat(toggle.isEnabled()).isFalse();
     }
 
+    @Test
+    public void setSwitchEnabled_shouldUpdateButtonEnabledState_beforeViewBound() {
+        final MasterSwitchPreference preference = new MasterSwitchPreference(mContext);
+        final PreferenceViewHolder holder = PreferenceViewHolder.createInstanceForTests(
+                LayoutInflater.from(mContext).inflate(
+                        R.layout.preference_widget_master_switch, null));
+        final Switch toggle = (Switch) holder.findViewById(R.id.switchWidget);
+
+        preference.setSwitchEnabled(false);
+        preference.onBindViewHolder(holder);
+        assertThat(toggle.isEnabled()).isFalse();
+    }
+
     @Test
     public void clickWidgetView_shouldToggleButton() {
         final MasterSwitchPreference preference = new MasterSwitchPreference(mContext);
@@ -108,6 +121,22 @@ public class MasterSwitchPreferenceTest {
         assertThat(toggle.isChecked()).isFalse();
     }
 
+    @Test
+    public void clickWidgetView_shouldNotToggleButtonIfDisabled() {
+        final MasterSwitchPreference preference = new MasterSwitchPreference(mContext);
+        final LayoutInflater inflater = LayoutInflater.from(mContext);
+        final PreferenceViewHolder holder = PreferenceViewHolder.createInstanceForTests(
+                inflater.inflate(R.layout.preference_two_target, null));
+        final LinearLayout widgetView = holder.itemView.findViewById(android.R.id.widget_frame);
+        inflater.inflate(R.layout.preference_widget_master_switch, widgetView, true);
+        final Switch toggle = (Switch) holder.findViewById(R.id.switchWidget);
+        preference.onBindViewHolder(holder);
+        toggle.setEnabled(false);
+
+        widgetView.performClick();
+        assertThat(toggle.isChecked()).isFalse();
+    }
+
     @Test
     public void clickWidgetView_shouldNotifyPreferenceChanged() {
         final MasterSwitchPreference preference = new MasterSwitchPreference(mContext);