Fix the BT settings is crashing after Toggle OFF/ON

Fix java NullPointerException since some object was not created
when users didn't performed BLE advertising.

Bug: 213610155
Bug: 242230899
Tag: #stability
Test: turn on/off Bluetooth in the setting then check if Bluetooth crashes happen.
Ignore-AOSP-First: patch for wear os
Change-Id: I3adccd699e10fef79579880f0110ae8474f36955

android/app/src/com/android/bluetooth/gatt/ContextMap.java

@@ -195,7 +195,8 @@ import java.util.UUID;
 
     private static final int ADVERTISE_STATE_MAX_SIZE = 5;
 
-    private EvictingQueue<AppAdvertiseStats> mLastAdvertises;
+    private final EvictingQueue<AppAdvertiseStats> mLastAdvertises =
+            EvictingQueue.create(ADVERTISE_STATE_MAX_SIZE);
 
     /** Internal list of connected devices **/
     private Set<Connection> mConnections = new HashSet<Connection>();
@@ -246,10 +247,6 @@ import java.util.UUID;
                 app = new App(appUid, callback, appName);
                 mApps.add(app);
             }
-
-            if (mLastAdvertises == null) {
-                mLastAdvertises = EvictingQueue.create(ADVERTISE_STATE_MAX_SIZE);
-            }
             return app;
         }
     }
@@ -630,7 +627,9 @@ import java.util.UUID;
             while (i.hasNext()) {
                 App entry = i.next();
                 entry.unlinkToDeath();
-                entry.appScanStats.isRegistered = false;
+                if (entry.appScanStats != null) {
+                    entry.appScanStats.isRegistered = false;
+                }
                 i.remove();
             }
         }