Fix visibility and editability of importance fields

- Block field should always be visible
- Locked by OEM: cannot block or change importance
- Locked by default app: cannot block, can change importance
- Locked by system app: cannot block, can change importance
- system app but blockable: can block, can change importance

Test: robotests
Fixes: 131248127
Change-Id: Ifa718c84573dd5125aefa4f672a79dc4f267d515

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

@@ -110,27 +110,13 @@ public abstract class NotificationPreferenceController extends AbstractPreferenc
         }
     }
 
-    private boolean isChannelConfigurable() {
-        if (mAppRow != null && mAppRow.lockedImportance) {
-            return false;
-        }
-        if (mChannel != null && mAppRow != null) {
-            return !Objects.equals(mChannel.getId(), mAppRow.lockedChannelId);
-        }
-        return false;
-    }
-
     protected boolean isChannelBlockable() {
         if (mChannel != null && mAppRow != null) {
-            if (!isChannelConfigurable()) {
+            if (mChannel.isImportanceLockedByCriticalDeviceFunction()
+                    || mChannel.isImportanceLockedByOEM()) {
                 return mChannel.getImportance() == IMPORTANCE_NONE;
             }
 
-            if (mChannel.isImportanceLockedByOEM()
-                    || mChannel.isImportanceLockedByCriticalDeviceFunction()) {
-                return false;
-            }
-
             return mChannel.isBlockableSystem() || !mAppRow.systemApp
                     || mChannel.getImportance() == IMPORTANCE_NONE;
         }