Add API to query if a UID is active

am: 0c1c9cd7f2

Change-Id: Ic209da2a6817b82e7bcc09bd6eb2c0896a4071f5

core/java/android/app/IActivityManager.aidl

@@ -94,6 +94,7 @@ interface IActivityManager {
     void registerUidObserver(in IUidObserver observer, int which, int cutpoint,
             String callingPackage);
     void unregisterUidObserver(in IUidObserver observer);
+    boolean isUidActive(int uid, String callingPackage);
     // =============== End of transactions used on native side as well ============================
 
     // Special low-level communication with activity manager.

services/core/java/com/android/server/am/ActivityManagerService.java

@@ -13941,6 +13941,18 @@ public class ActivityManagerService extends IActivityManager.Stub
         }
     }
 
+    @Override
+    public boolean isUidActive(int uid, String callingPackage) {
+        if (!hasUsageStatsPermission(callingPackage)) {
+            enforceCallingPermission(android.Manifest.permission.PACKAGE_USAGE_STATS,
+                    "getPackageProcessState");
+        }
+        synchronized (this) {
+            final UidRecord uidRecord = mActiveUids.get(uid);
+            return uidRecord != null && !uidRecord.setIdle;
+        }
+    }
+
     @Override
     public boolean convertFromTranslucent(IBinder token) {
         final long origId = Binder.clearCallingIdentity();