Vibrator: Allow priority vibrations in low-power mode for accessibility.

This is mainly for Wear devices that don't have speakers.

Bug: 37543478

Test: Manual:
1. Activate low power mode `adb shell dumpsys battery unplug && adb shell settings put global low_power 1`
2. Then see if Alarm/Timer will vibrate.
3. Send a Hangout Test notification, make sure it does NOT vibrate.

On phones there should be no change. Alarms will not vibrate.

Change-Id: Ia6dffa7e528886e7c84390dbb33b44f298c7afa4

core/res/res/values/config.xml

@@ -2531,6 +2531,10 @@
     <!-- The default vibration strength, must be between 1 and 255 inclusive. -->
     <integer name="config_defaultVibrationAmplitude">255</integer>
 
+    <!-- If the device should still vibrate even in low power mode, for certain priority vibrations
+     (e.g. accessibility, alarms). This is mainly for Wear devices that don't have speakers. -->
+    <bool name="config_allowPriorityVibrationsInLowPowerMode">false</bool>
+
     <!-- Number of retries Cell Data should attempt for a given error code before
          restarting the modem.
          Error codes not listed will not lead to modem restarts.

core/res/res/values/symbols.xml

@@ -1808,6 +1808,7 @@
   <java-symbol type="dimen" name="default_minimal_size_pip_resizable_task" />
   <java-symbol type="dimen" name="task_height_of_minimized_mode" />
   <java-symbol type="fraction" name="config_screenAutoBrightnessDozeScaleFactor" />
+  <java-symbol type="bool" name="config_allowPriorityVibrationsInLowPowerMode" />
   <java-symbol type="fraction" name="config_autoBrightnessAdjustmentMaxGamma" />
   <java-symbol type="integer" name="config_autoBrightnessAmbientLightHorizon"/>
   <java-symbol type="integer" name="config_autoBrightnessBrighteningLightDebounce"/>

services/core/java/com/android/server/VibratorService.java

@@ -73,6 +73,7 @@ public class VibratorService extends IVibratorService.Stub
 
     private final LinkedList<VibrationInfo> mPreviousVibrations;
     private final int mPreviousVibrationsLimit;
+    private final boolean mAllowPriorityVibrationsInLowPowerMode;
     private final boolean mSupportsAmplitudeControl;
     private final int mDefaultVibrationAmplitude;
     private final VibrationEffect[] mFallbackEffects;
@@ -213,6 +214,9 @@ public class VibratorService extends IVibratorService.Stub
         mDefaultVibrationAmplitude = mContext.getResources().getInteger(
                 com.android.internal.R.integer.config_defaultVibrationAmplitude);
 
+        mAllowPriorityVibrationsInLowPowerMode = mContext.getResources().getBoolean(
+                com.android.internal.R.bool.config_allowPriorityVibrationsInLowPowerMode);
+
         mPreviousVibrations = new LinkedList<>();
 
         IntentFilter filter = new IntentFilter();
@@ -456,7 +460,7 @@ public class VibratorService extends IVibratorService.Stub
     }
 
     private void startVibrationLocked(final Vibration vib) {
-        if (mLowPowerMode && vib.mUsageHint != AudioAttributes.USAGE_NOTIFICATION_RINGTONE) {
+        if (!isAllowedToVibrate(vib)) {
             if (DEBUG) {
                 Slog.e(TAG, "Vibrate ignored, low power mode");
             }
@@ -505,6 +509,26 @@ public class VibratorService extends IVibratorService.Stub
         }
     }
 
+    private boolean isAllowedToVibrate(Vibration vib) {
+        if (!mLowPowerMode) {
+            return true;
+        }
+        if (vib.mUsageHint == AudioAttributes.USAGE_NOTIFICATION_RINGTONE) {
+            return true;
+        }
+        if (!mAllowPriorityVibrationsInLowPowerMode) {
+            return false;
+        }
+        if (vib.mUsageHint == AudioAttributes.USAGE_ALARM ||
+            vib.mUsageHint == AudioAttributes.USAGE_ASSISTANCE_ACCESSIBILITY ||
+            vib.mUsageHint == AudioAttributes.USAGE_NOTIFICATION_COMMUNICATION_REQUEST) {
+
+            return true;
+        }
+
+        return false;
+    }
+
     private boolean shouldVibrateForRingtone() {
         AudioManager audioManager = (AudioManager) mContext.getSystemService(Context.AUDIO_SERVICE);
         int ringerMode = audioManager.getRingerModeInternal();