Ensure cdm clear cache command persists state

This CL ensures that the clear-association-memory-cache shell command
immediately persists all user state before dumping clearing caches.
This prevents state change updates from getting lost.

This is not a critical issue because this shell command is only used
for testing, but it allows for more graceful and reliable test code.

Test: atest CtsCompanionDeviceManagerCoreTestCases
Test: atest CtsCompanionDeviceManagerUiAutomationTestCases
Change-Id: Ib981862c587a86bce57c4a5d67c7c18a40b47235

services/companion/java/com/android/server/companion/CompanionDeviceManagerService.java

@@ -77,6 +77,7 @@ import android.content.pm.PackageInfo;
 import android.content.pm.PackageItemInfo;
 import android.content.pm.PackageManager;
 import android.content.pm.PackageManagerInternal;
+import android.content.pm.UserInfo;
 import android.net.MacAddress;
 import android.net.NetworkPolicyManager;
 import android.os.Binder;
@@ -1358,6 +1359,17 @@ public class CompanionDeviceManagerService extends SystemService
         }
     }
 
+    /**
+     * This method must only be called from {@link CompanionDeviceShellCommand} for testing
+     * purposes only!
+     */
+    void persistState() {
+        mUserPersistenceHandler.clearMessages();
+        for (UserInfo user : mUserManager.getAliveUsers()) {
+            persistStateForUser(user.id);
+        }
+    }
+
     /**
      * This class is dedicated to handling requests to persist user state.
      */
@@ -1376,6 +1388,13 @@ public class CompanionDeviceManagerService extends SystemService
             }
         }
 
+        /**
+         * Clears *ALL* outstanding persist requests for *ALL* users.
+         */
+        synchronized void clearMessages() {
+            removeCallbacksAndMessages(null);
+        }
+
         @Override
         public void handleMessage(@NonNull Message msg) {
             final int userId = msg.what;

services/companion/java/com/android/server/companion/CompanionDeviceShellCommand.java

@@ -83,6 +83,7 @@ class CompanionDeviceShellCommand extends android.os.ShellCommand {
                 }
                 break;
                 case "clear-association-memory-cache": {
+                    mService.persistState();
                     mService.loadAssociationsFromDisk();
                 }
                 break;