Added client.cpp and server.cpp

Did not build or test.
diff --git a/aidl/client.cpp b/aidl/client.cpp
new file mode 100644
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--- /dev/null
+++ b/aidl/client.cpp
@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2020 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.
+ */
+
+#include <binder/IBinder.h>
+#include <binder/IInterface.h>
+#include <binder/IPCThreadState.h>
+#include <binder/IServiceManager.h>
+#include <binder/ProcessState.h>
+#include <binder/TextOutput.h>
+#include <foo/BpFoo.h>
+#include <stdlib.h>
+#include <utils/Log.h>
+#include <utils/RefBase.h>
+
+using namespace android;
+
+int main(int argc, char** argv) {
+  sp<IServiceManager> sm = defaultServiceManager();
+  sp<IBinder> binder = sm->getService(String16("foo.IFoo"));
+  // TODO: Assert that binder is not 0.
+  sp<IFoo> demo = interface_cast<IFoo>(binder);
+  int sum = demo->add(1, 2);
+  // TODO: Assert result.
+  return 0;
+}
diff --git a/aidl/server.cpp b/aidl/server.cpp
new file mode 100644
index 0000000..124eba9
--- /dev/null
+++ b/aidl/server.cpp
@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2020 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.
+ */
+
+#include <binder/IBinder.h>
+#include <binder/IInterface.h>
+#include <binder/IPCThreadState.h>
+#include <binder/IServiceManager.h>
+#include <binder/ProcessState.h>
+#include <binder/TextOutput.h>
+#include <foo/BnFoo.h>
+#include <stdlib.h>
+#include <utils/Log.h>
+#include <utils/RefBase.h>
+
+using namespace android;
+
+class Demo : public foo::BnFoo {
+  virtual ::android::binder::Status add(int32_t a, int32_t b,
+                                        int32_t* _aidl_return) {
+    *_aidl_return = a + b;
+    return ::android::OK;
+  }
+}
+
+int main(int argc, char** argv) {
+  defaultServiceManager()->addService(String16("foo.IFoo", new Demo()));
+  android::ProcessState::self()->startThreadPool();
+  IPCThreadState::self()->joinThreadPool();
+  return 0;
+}