Add proxy for BackupManager

This allows injection of BackupManagerProxy instead of directly
referencing BackupManager's static functions. This allows testing of
BackupManager calls.

Test: existing tests pass
BUG: 254030424
Change-Id: I38a0dba16ee2fa16f8af01896531be78cc178a9e

packages/SystemUI/src/com/android/systemui/util/BackupManagerProxy.kt

@@ -0,0 +1,17 @@
+package com.android.systemui.util
+
+import android.app.backup.BackupManager
+import com.android.systemui.dagger.SysUISingleton
+import javax.inject.Inject
+
+/** Wrapper around [BackupManager] useful for testing. */
+@SysUISingleton
+class BackupManagerProxy @Inject constructor() {
+
+    /** Wrapped version of [BackupManager.dataChanged] */
+    fun dataChanged(packageName: String) = BackupManager.dataChanged(packageName)
+
+    /** Wrapped version of [BackupManager.dataChangedForUser] */
+    fun dataChangedForUser(userId: Int, packageName: String) =
+        BackupManager.dataChangedForUser(userId, packageName)
+}