Change Android activity title from JNI call

platform_tools/android/apps/viewer/src/main/java/org/skia/viewer/ViewerActivity.java

Index: platform_tools/android/apps/viewer/src/main/java/org/skia/viewer/ViewerActivity.java
diff --git a/platform_tools/android/apps/viewer/src/main/java/org/skia/viewer/ViewerActivity.java b/platform_tools/android/apps/viewer/src/main/java/org/skia/viewer/ViewerActivity.java
index e3260c25f7389dbec24cca19be0773510d1251dd..d6fe710aeb0fa8fa0f8a3b9daf2f8f11886de67b 100644
--- a/platform_tools/android/apps/viewer/src/main/java/org/skia/viewer/ViewerActivity.java
+++ b/platform_tools/android/apps/viewer/src/main/java/org/skia/viewer/ViewerActivity.java
@@ -60,6 +60,7 @@ public class ViewerActivity
         setContentView(R.layout.activity_main);
 
         mApplication = (ViewerApplication) getApplication();
+        mApplication.setViewerActivity(this);
         mView = (SurfaceView) findViewById(R.id.surfaceView);
         mView.getHolder().addCallback(this);
 
@@ -67,6 +68,12 @@ public class ViewerActivity
     }
 
     @Override
+    protected void onDestroy() {
+        mApplication.setViewerActivity(null);
+        super.onDestroy();
+    }
+
+    @Override
     public void surfaceCreated(SurfaceHolder holder) {
         if (mApplication.getNativeHandle() != 0) {
             onSurfaceCreated(mApplication.getNativeHandle(), holder.getSurface());