Add stubs and an sdk definition for sdkext

This defines both publicapi and a systemapi variants, even though
the publicapi is currently empty. Uses the newly defined module
stub_defaults.

Bug: 137191822
Test: m framework
Test: m sdkext-sdk
Change-Id: Idad8902054bef4a08953f4677689506566f146d8

Android.bp

@@ -458,7 +458,8 @@ java_library {
     installable: false, // this lib is a build-only library
     static_libs: [
         "framework-minus-apex",
-        // TODO(jiyong): add stubs for APEXes here
+        "framework-sdkext-stubs-systemapi",
+        // TODO(jiyong): add more stubs for APEXes here
     ],
     sdk_version: "core_platform",
 }

apex/sdkext/Android.bp

@@ -25,6 +25,11 @@ apex {
     certificate: ":com.android.sdkext.certificate",
 }
 
+sdk {
+    name: "sdkext-sdk",
+    java_libs: [ "framework-sdkext-stubs-systemapi" ],
+}
+
 apex_key {
     name: "com.android.sdkext.key",
     public_key: "com.android.sdkext.avbpubkey",

apex/sdkext/framework/Android.bp

@@ -28,3 +28,34 @@ java_library {
     permitted_packages: [ "android.os.ext" ],
     installable: true,
 }
+
+droidstubs {
+    name: "framework-sdkext-droidstubs-publicapi",
+    defaults: [
+        "framework-sdkext-stubs-defaults",
+        "framework-module-stubs-defaults-publicapi",
+    ]
+}
+
+droidstubs {
+    name: "framework-sdkext-droidstubs-systemapi",
+    defaults: [
+        "framework-sdkext-stubs-defaults",
+        "framework-module-stubs-defaults-systemapi",
+    ]
+}
+
+stubs_defaults {
+    name: "framework-sdkext-stubs-defaults",
+    srcs: [
+        ":framework-sdkext-sources",
+        ":framework-annotations",
+    ],
+    sdk_version: "system_current",
+}
+
+java_library {
+    name: "framework-sdkext-stubs-systemapi",
+    srcs: [":framework-sdkext-droidstubs-systemapi"],
+    sdk_version: "system_current",
+}