Add API signature files for the system server APIs

... so that they can be reviewed.

Bug: 140202860
Test: m
Change-Id: Iec8cdd30ad5e4979d56140a8c00a85af6476f67f
diff --git a/services/Android.bp b/services/Android.bp
index 501496d..ede4c3e 100644
--- a/services/Android.bp
+++ b/services/Android.bp
@@ -119,6 +119,12 @@
         " --hide DeprecationMismatch" +
         " --hide HiddenTypedefConstant",
     visibility: ["//visibility:private"],
+    check_api: {
+        current: {
+            api_file: "api/current.txt",
+            removed_api_file: "api/removed.txt",
+        },
+    },
 }
 
 java_library {
diff --git a/services/api/current.txt b/services/api/current.txt
new file mode 100644
index 0000000..d802177
--- /dev/null
+++ b/services/api/current.txt
@@ -0,0 +1 @@
+// Signature format: 2.0
diff --git a/services/api/removed.txt b/services/api/removed.txt
new file mode 100644
index 0000000..d802177
--- /dev/null
+++ b/services/api/removed.txt
@@ -0,0 +1 @@
+// Signature format: 2.0