Reland WM Extensions for all devices

The revert is because there is a prebuilt app using an outdated
unreleased sidecar API (from 2022).

Bug: 306666082
Test: pass the failure test
Change-Id: I74f5f6cff84d7f26466ccdea8bcc982bc363a5d3

target/product/base_system_ext.mk

@@ -28,3 +28,6 @@ PRODUCT_PACKAGES += \
 PRODUCT_PACKAGES_SHIPPING_API_LEVEL_34 += \
     hwservicemanager \
     android.hidl.allocator@1.0-service \
+
+# Window Extensions
+$(call inherit-product, $(SRC_TARGET_DIR)/product/window_extensions_base.mk)

target/product/window_extensions.mk

@@ -14,11 +14,14 @@
 # limitations under the License.
 #
 
-# /system_ext packages
-PRODUCT_PACKAGES += \
-    androidx.window.extensions \
-    androidx.window.sidecar
-
-# properties
+# Extension of window_extensions_base.mk to enable the activity embedding
+# feature for all apps by default. All large screen devices must inherit
+# this in build. Optional for other form factors.
+#
+# Indicated whether the Activity Embedding feature should be guarded by
+# Android 15 to avoid app compat impact.
+# If true (or not set), the feature is only enabled for apps with target
+# SDK of Android 15 or above.
+# If false, the feature is enabled for all apps.
 PRODUCT_PRODUCT_PROPERTIES += \
-    persist.wm.extensions.enabled=true
+    persist.wm.extensions.activity_embedding_guard_with_android_15=false

target/product/window_extensions_base.mk

@@ -0,0 +1,34 @@
+#
+# Copyright (C) 2024 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.
+#
+
+# The base version of window_extensions.mk to be included on all devices.
+# Devices that don't support multi-window can choose to drop this.
+# TODO(b/326009200): Remove from build that doesn't support multi-window.
+#
+# Note: by default the Activity Embedding feature is guarded by app's
+# targetSDK on Android 15 to avoid app compat impact.
+#
+# Large screen devices must inherit window_extensions.mk to enable the
+# Activity Embedding feature for all apps.
+
+# /system_ext packages
+PRODUCT_PACKAGES += \
+    androidx.window.extensions \
+    androidx.window.sidecar
+
+# properties
+PRODUCT_PRODUCT_PROPERTIES += \
+    persist.wm.extensions.enabled=true