Update the "When to dream" settings

For devices which don't support dreaming on battery, we can offer
simpler options since the device must always be charging for
screensavers to appear. Therefore there are only two options:

1. While charging
2. While docked and charging

Test: flashed and verified on device
Test: make -j64 RunSettingsRoboTests
Fixes: 226187572
Change-Id: I6ed24cda8874f2fb941f6cfded9ed97ed78a3cb6

src/com/android/settings/dream/WhenToDreamPicker.java

@@ -32,12 +32,15 @@ public class WhenToDreamPicker extends RadioButtonPickerFragment {
 
     private static final String TAG = "WhenToDreamPicker";
     private DreamBackend mBackend;
+    private boolean mDreamsSupportedOnBattery;
 
     @Override
     public void onAttach(Context context) {
         super.onAttach(context);
 
         mBackend = DreamBackend.getInstance(context);
+        mDreamsSupportedOnBattery = getResources().getBoolean(
+                com.android.internal.R.bool.config_dreamsEnabledOnBattery);
     }
 
     @Override
@@ -69,11 +72,17 @@ public class WhenToDreamPicker extends RadioButtonPickerFragment {
     }
 
     private String[] entries() {
-        return getResources().getStringArray(R.array.when_to_start_screensaver_entries);
+        if (mDreamsSupportedOnBattery) {
+            return getResources().getStringArray(R.array.when_to_start_screensaver_entries);
+        }
+        return getResources().getStringArray(R.array.when_to_start_screensaver_entries_no_battery);
     }
 
     private String[] keys() {
-        return getResources().getStringArray(R.array.when_to_start_screensaver_values);
+        if (mDreamsSupportedOnBattery) {
+            return getResources().getStringArray(R.array.when_to_start_screensaver_values);
+        }
+        return getResources().getStringArray(R.array.when_to_start_screensaver_values_no_battery);
     }
 
     @Override