Merge "Add AMS lock protection to mAppsInBackgroundRestricted collection" into tm-qpr-dev am: 96efd6153a

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/19245813

Change-Id: I7576261b5fd57a21c8269ceb32703b2789616a7c
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

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

@@ -2269,7 +2269,9 @@ public final class ProcessList {
                 final boolean inBgRestricted = ast.isAppBackgroundRestricted(
                         app.info.uid, app.info.packageName);
                 if (inBgRestricted) {
-                    mAppsInBackgroundRestricted.add(app);
+                    synchronized (mService) {
+                        mAppsInBackgroundRestricted.add(app);
+                    }
                 }
                 app.mState.setBackgroundRestricted(inBgRestricted);
             }