Reintroduce button-backlight (and respective inactivity timeout)

The power manager rewrite from Change I1d7a52e98f0449f76d70bf421f6a7f245957d1d7
completely removed support for control of the button backlights, which makes
all capacitive buttons out there stay dark. The commit message in that change
mentions it hasn't been implemented _yet_, so this fix should be temporary
until upstream does their own implementation

[RC: Updated to 5.0]

Change-Id: I6094c446e0b8c23f57d30652a3cbd35dee5e821a

services/core/java/com/android/server/display/DisplayPowerController.java

@@ -20,6 +20,7 @@
 import com.android.internal.app.IBatteryStats;
 import com.android.server.LocalServices;
 import com.android.server.am.BatteryStatsService;
+import com.android.server.lights.LightsManager;
 
 import android.animation.Animator;
 import android.animation.ObjectAnimator;
@@ -129,6 +130,9 @@ final class DisplayPowerController implements AutomaticBrightnessController.Call
     // Battery stats.
     private final IBatteryStats mBatteryStats;
 
+    // The lights service.
+    private final LightsManager mLights;
+
     // The sensor manager.
     private final SensorManager mSensorManager;
 
@@ -300,6 +304,7 @@ public DisplayPowerController(Context context,
         mCallbacks = callbacks;
 
         mBatteryStats = BatteryStatsService.getService();
+        mLights = LocalServices.getService(LightsManager.class);
         mSensorManager = sensorManager;
         mWindowManagerPolicy = LocalServices.getService(WindowManagerPolicy.class);
         mBlanker = blanker;
@@ -678,6 +683,12 @@ private void updatePowerState() {
         // Use zero brightness when screen is off.
         if (state == Display.STATE_OFF) {
             brightness = PowerManager.BRIGHTNESS_OFF;
+            mLights.getLight(LightsManager.LIGHT_ID_BUTTONS).setBrightness(brightness);
+        }
+
+        // Disable button lights when dozing
+        if (state == Display.STATE_DOZE || state == Display.STATE_DOZE_SUSPEND) {
+            mLights.getLight(LightsManager.LIGHT_ID_BUTTONS).setBrightness(PowerManager.BRIGHTNESS_OFF);
         }
 
         // Configure auto-brightness.

services/core/java/com/android/server/power/PowerManagerService.java

@@ -220,6 +220,8 @@ public final class PowerManagerService extends SystemService
     private static final int HALT_MODE_REBOOT = 1;
     private static final int HALT_MODE_REBOOT_SAFE_MODE = 2;
 
+    private static final int BUTTON_ON_DURATION = 5 * 1000;
+
     // File location for last reboot reason
     private static final String LAST_REBOOT_LOCATION = "/data/misc/reboot/last_reboot_reason";
 
@@ -240,6 +242,7 @@ public final class PowerManagerService extends SystemService
     private SettingsObserver mSettingsObserver;
     private DreamManagerInternal mDreamManager;
     private Light mAttentionLight;
+    private Light mButtonsLight;
 
     private final Object mLock = LockGuard.installNewLock(LockGuard.INDEX_POWER);
 
@@ -747,6 +750,7 @@ mAppOps, createSuspendBlockerLocked("PowerManagerService.Broadcasts"),
 
             mLightsManager = getLocalService(LightsManager.class);
             mAttentionLight = mLightsManager.getLight(LightsManager.LIGHT_ID_ATTENTION);
+            mButtonsLight = mLightsManager.getLight(LightsManager.LIGHT_ID_BUTTONS);
 
             // Initialize display power management.
             mDisplayManagerInternal.initPowerManagement(
@@ -1947,6 +1951,12 @@ private void updateUserActivitySummaryLocked(long now, int dirty) {
                     nextTimeout = mLastUserActivityTime
                             + screenOffTimeout - screenDimDuration;
                     if (now < nextTimeout) {
+                        if (now > mLastUserActivityTime + BUTTON_ON_DURATION) {
+                            mButtonsLight.setBrightness(0);
+                        } else {
+                            mButtonsLight.setBrightness(mDisplayPowerRequest.screenBrightness);
+                            nextTimeout = now + BUTTON_ON_DURATION;
+                        }
                         mUserActivitySummary = USER_ACTIVITY_SCREEN_BRIGHT;
                     } else {
                         nextTimeout = mLastUserActivityTime + screenOffTimeout;