Add native bindings for getNamesForUids

A new API [getNamesForUids] was recently added to the PackageManager
and this API needs to be accessible to native code. However, there
were two constraints:
1) Instead of hand-rolling the binder, we wanted to auto generate
the bindings directly from the AIDL compiler.
2) We didn't want to expose/annotate all 180+ PackageManager APIs
when only a single API is needed.
So, we chose to create a parallel API that can be used explicitly
for native bindings without exposing the entirety of the
PackageManager.

Bug: 62805090
Test: Manual
Test: Create a native application that calls into the new service
Test: See the call works and data and returned
Change-Id: Icdcb5c825fdc08d029b0eaed5c5be49cce40c9d8
diff --git a/libs/binder/Android.bp b/libs/binder/Android.bp
index 748105c..701e698 100644
--- a/libs/binder/Android.bp
+++ b/libs/binder/Android.bp
@@ -66,8 +66,13 @@
         "TextOutput.cpp",
         "IpPrefix.cpp",
         "Value.cpp",
+        "aidl/android/content/pm/IPackageManagerNative.aidl",
     ],
 
+    aidl: {
+        export_aidl_headers: true,
+    },
+
     cflags: [
         "-Wall",
         "-Wextra",
diff --git a/libs/binder/aidl/android/content/pm/IPackageManagerNative.aidl b/libs/binder/aidl/android/content/pm/IPackageManagerNative.aidl
new file mode 100644
index 0000000..6b7254c
--- /dev/null
+++ b/libs/binder/aidl/android/content/pm/IPackageManagerNative.aidl
@@ -0,0 +1,41 @@
+/*
+**
+** Copyright 2017, 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 android.content.pm;
+
+/**
+ * Parallel implementation of certain {@link PackageManager} APIs that need to
+ * be exposed to native code.
+ * <p>These APIs are a parallel definition to the APIs in PackageManager, so,
+ * they can technically diverge. However, it's good practice to keep these
+ * APIs in sync with each other.
+ * <p>Because these APIs are exposed to native code, it's possible they will
+ * be exposed to privileged components [such as UID 0]. Care should be taken
+ * to avoid exposing potential security holes for methods where permission
+ * checks are bypassed based upon UID alone.
+ *
+ * @hide
+ */
+interface IPackageManagerNative {
+    /**
+     * Returns a set of names for the given UIDs.
+     * IMPORTANT: Unlike the Java version of this API, unknown UIDs are
+     * not represented by 'null's. Instead, they are represented by empty
+     * strings.
+     */
+    @utf8InCpp String[] getNamesForUids(in int[] uids);
+}