Improve debuglog submission.

app/src/main/java/org/thoughtcrime/securesms/components/ListenableHorizontalScrollView.java

@@ -0,0 +1,40 @@
+package org.thoughtcrime.securesms.components;
+
+import android.content.Context;
+import android.util.AttributeSet;
+import android.widget.HorizontalScrollView;
+
+import androidx.annotation.Nullable;
+
+/**
+ * Unfortunately {@link HorizontalScrollView#setOnScrollChangeListener(OnScrollChangeListener)}
+ * wasn't added until API 23, so now we have to do this ourselves.
+ */
+public class ListenableHorizontalScrollView extends HorizontalScrollView {
+
+  private OnScrollListener listener;
+
+  public ListenableHorizontalScrollView(Context context) {
+    super(context);
+  }
+
+  public ListenableHorizontalScrollView(Context context, AttributeSet attrs) {
+    super(context, attrs);
+  }
+
+  public void setOnScrollListener(@Nullable OnScrollListener listener) {
+    this.listener = listener;
+  }
+
+  @Override
+  protected void onScrollChanged(int newLeft, int newTop, int oldLeft, int oldTop) {
+    if (listener != null) {
+      listener.onScroll(newLeft, oldLeft);
+    }
+    super.onScrollChanged(newLeft, newTop, oldLeft, oldTop);
+  }
+
+  public interface OnScrollListener {
+    void onScroll(int newLeft, int oldLeft);
+  }
+}