Migrate IRegionSamplingListener interface to AIDL

This addresses security vulnerabilities due to hard coded binder
interface.

Bug: 195660647
Test: (1) atest RegionSamplingTest
      (2) install Google I/O 2019 app, tap Agenda menu, scrolling to
      examine the bottom horizontal bar color changes
Change-Id: If2d33c5168b2df5fc7fd8f55e3bca75d3f385a89
diff --git a/libs/gui/tests/RegionSampling_test.cpp b/libs/gui/tests/RegionSampling_test.cpp
index 6746b0a..c9106be 100644
--- a/libs/gui/tests/RegionSampling_test.cpp
+++ b/libs/gui/tests/RegionSampling_test.cpp
@@ -17,9 +17,9 @@
 #include <gtest/gtest.h>
 #include <thread>
 
+#include <android/gui/BnRegionSamplingListener.h>
 #include <binder/ProcessState.h>
 #include <gui/DisplayEventReceiver.h>
-#include <gui/IRegionSamplingListener.h>
 #include <gui/ISurfaceComposer.h>
 #include <gui/Surface.h>
 #include <gui/SurfaceComposerClient.h>
@@ -135,12 +135,13 @@
     std::atomic<bool> poll_{true};
 };
 
-struct Listener : BnRegionSamplingListener {
-    void onSampleCollected(float medianLuma) override {
+struct Listener : android::gui::BnRegionSamplingListener {
+    binder::Status onSampleCollected(float medianLuma) override {
         std::unique_lock<decltype(mutex)> lk(mutex);
         received = true;
         mLuma = medianLuma;
         cv.notify_all();
+        return binder::Status::ok();
     };
     bool wait_event(std::chrono::milliseconds timeout) {
         std::unique_lock<decltype(mutex)> lk(mutex);