Notify about brightness change when screen turns on

Bug: 216419091
Test: ROBOTEST_FILTER=BrightnessLevelPreferenceControllerTest m -j RunSettingsRoboTests
Change-Id: I35f4b81b325a7275ad7391aa631d183ddcbd8fe3

src/com/android/settings/display/BrightnessLevelPreferenceController.java

@@ -141,6 +141,7 @@ public class BrightnessLevelPreferenceController extends AbstractPreferenceContr
         mContentResolver.registerContentObserver(BRIGHTNESS_ADJ_URI, false, mBrightnessObserver);
         mDisplayManager.registerDisplayListener(mDisplayListener, mHandler,
                 DisplayManager.EVENT_FLAG_DISPLAY_BRIGHTNESS);
+        updatedSummary(mPreference);
     }
 
     @Override

tests/robotests/src/com/android/settings/display/BrightnessLevelPreferenceControllerTest.java

@@ -135,6 +135,21 @@ public class BrightnessLevelPreferenceControllerTest {
                 System.getUriFor(System.SCREEN_AUTO_BRIGHTNESS_ADJ))).isEmpty();
     }
 
+    @Test
+    public void onStart_shouldSetSummary() {
+        BrightnessLevelPreferenceController controller =
+                new BrightnessLevelPreferenceController(mContext, null);
+        controller.displayPreference(mScreen);
+
+        controller.onStop();
+        when(mDisplay.getBrightnessInfo()).thenReturn(
+                new BrightnessInfo(0.5f, 0.0f, 1.0f, BrightnessInfo.HIGH_BRIGHTNESS_MODE_OFF,
+                        0.5f, BrightnessInfo.BRIGHTNESS_MAX_REASON_NONE));
+        controller.onStart();
+
+        verify(mPreference).setSummary("87%");
+    }
+
     @Test
     public void updateState_inVrMode_shouldSetSummaryToVrBrightness() {
         doReturn(true).when(mController).isInVrMode();