Migrate UsageStats to Spa

The UsageStats page is for testing only, cannot entry through Settings
Home, but is accessible by enter *#*#4636#*#* in dialer.

Migrate UsageStats to Spa for both improving the UI & performance.

Fix: 244675756
Bug: 235727273
Test: Manual with Settings App
Change-Id: I6ec6e233075a3f79ac1231aecafabf2a71dac716

src/com/android/settings/spa/SpaBridgeActivity.kt

@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.settings.spa
+
+import android.app.Activity
+import android.content.pm.PackageManager
+import android.content.pm.PackageManager.ComponentInfoFlags
+import android.os.Bundle
+import com.android.settings.spa.SpaActivity.Companion.startSpaActivity
+
+/**
+ * Activity used as a bridge to [SpaActivity].
+ *
+ * Since [SpaActivity] is not exported, [SpaActivity] could not be the target activity of
+ * <activity-alias>, otherwise all its pages will be exported.
+ * So need this bridge activity to sit in the middle of <activity-alias> and [SpaActivity].
+ */
+class SpaBridgeActivity : Activity() {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        getDestination()?.let { destination ->
+            startSpaActivity(this, destination)
+        }
+        finish()
+    }
+
+    private fun getDestination(): String? =
+        packageManager.getActivityInfo(
+            componentName, ComponentInfoFlags.of(PackageManager.GET_META_DATA.toLong())
+        ).metaData.getString(META_DATA_KEY_DESTINATION)
+
+    companion object {
+        private const val META_DATA_KEY_DESTINATION = "com.android.settings.spa.DESTINATION"
+    }
+}