Update codelab system app to use native code

Bug: b/291771121
Test: tested on local devices
Change-Id: I1532d89ef185c584d3cc76c0541a0f47e622e3fb
Merged-In: I1532d89ef185c584d3cc76c0541a0f47e622e3fb

samples/AconfigDemo/Android.bp

@@ -8,13 +8,16 @@ android_app {
     srcs: [
         "src/**/*.java"
     ],
+    platform_apis: true,
     certificate: "platform",
-    sdk_version: "current",
     static_libs: [
         "ContentLibs",
         "dagger2",
         "jsr330",
     ],
+    jni_libs: [
+        "libexample_cpp_lib",
+    ],
     optimize: {
         enabled: true,
         proguard_compatibility: false,
@@ -35,7 +38,7 @@ aconfig_declarations {
 
 
 java_aconfig_library {
-    name: "aconfig_demo_flags_lib",
+    name: "aconfig_demo_flags_java_lib",
     aconfig_declarations: "aconfig_demo_flags",
 }
 
@@ -53,7 +56,34 @@ java_library {
     ],
     sdk_version: "current",
     static_libs: [
-        "aconfig_demo_flags_lib",
+        "aconfig_demo_flags_java_lib",
     ],
     libs: ["jsr330"],
 }
+
+cc_aconfig_library {
+    name: "aconfig_demo_flags_c_lib",
+    aconfig_declarations: "aconfig_demo_flags",
+}
+
+cc_library {
+    name: "libexample_cpp_lib",
+    srcs: ["src/example_cpp_lib.cc"],
+    double_loadable: true,
+    cflags: [
+        "-Wall",
+        "-Werror",
+        "-Wno-unused-function",
+        "-Wno-unused-parameter",
+    ],
+    header_libs: [
+      "jni_headers",
+    ],
+    shared_libs: [
+        "server_configurable_flags",
+    ],
+    static_libs: [
+        "aconfig_demo_flags_c_lib",
+    ],
+    export_include_dirs: ["src/include"],
+}

samples/AconfigDemo/aconfig_demo_flags.aconfig

@@ -28,6 +28,13 @@ flag {
   bug: "287644619"
 }
 
+flag {
+    name: "fifth_flag"
+    namespace: "configuration"
+    description: "The fifth flag, added right after the first three flags."
+    bug: "287644619"
+}
+
 flag {
   name: "third_flag"
   namespace: "configuration"

samples/AconfigDemo/src/com/example/android/aconfig/demo/AconfigDemoActivity.java

@@ -43,13 +43,16 @@ public class AconfigDemoActivity extends Activity {
 
         setContentView(R.layout.main);
         TextView simpleTextView = (TextView) findViewById(R.id.simpleTextView);
-        simpleTextView.setText("Show Flags: \n\n");
+        simpleTextView.setText("Show Java Flags: \n\n");
 
         StaticContent cp = new StaticContent();
         simpleTextView.append(cp.getContent());
 
         simpleTextView.append(injectedContent.getContent());
 
+        simpleTextView.append("Show C/C++ Flags: \n\n");
+        simpleTextView.append(printCFlag());
+
         if (Flags.awesomeFlag1()) {
             Log.v("AconfigDemoActivity", Flags.FLAG_AWESOME_FLAG_1 + " is on!");
         }
@@ -58,5 +61,10 @@ public class AconfigDemoActivity extends Activity {
             Log.v("AconfigDemoActivity", Flags.FLAG_AWESOME_FLAG_2 + " is on!");
         }
     }
-}
 
+    public native String printCFlag();
+
+    static {
+        System.loadLibrary("example_cpp_lib");
+    }
+}

samples/AconfigDemo/src/example_cpp_lib.cc

@@ -0,0 +1,34 @@
+#include "example_cpp_lib.h"
+#include <string>
+#include <com_example_android_aconfig_demo_flags.h>
+
+namespace demo_flags = com::example::android::aconfig::demo::flags;
+
+// use static methods interface
+static std::string get_flag_via_static_interface() {
+  return std::string("flag value : ") +
+      (demo_flags::append_static_content() ? "true" : "false");
+}
+
+// use flag provider for injection interface
+static std::string get_flag_via_injection_interface(
+  demo_flags::flag_provider_interface* provider) {
+  return std::string("flag value : ") +
+      ((provider->append_injected_content()) ? "true" : "false");
+}
+
+jstring Java_com_example_android_aconfig_demo_AconfigDemoActivity_printCFlag(
+    JNIEnv* env,
+    jobject thiz) {
+  auto result = std::string("flag name : append_static_content\n");
+  result += "use pattern : static method\n";
+  result += get_flag_via_static_interface();
+
+  result += "\n\n";
+
+  result += "flag name : append_injected_content\n";
+  result += "use pattern : injection\n";
+  result += get_flag_via_injection_interface(demo_flags::provider_.get());
+
+  return env->NewStringUTF(result.c_str());
+}

samples/AconfigDemo/src/include/example_cpp_lib.h

@@ -0,0 +1,7 @@
+#pragma once
+
+#include <jni.h>
+
+extern "C" jstring Java_com_example_android_aconfig_demo_AconfigDemoActivity_printCFlag(
+    JNIEnv* env,
+    jobject thiz);