WelcomeActivity: properly implement edge-to-edge

src/main/java/org/thoughtcrime/securesms/WelcomeActivity.java

@@ -38,6 +38,7 @@ import org.thoughtcrime.securesms.service.NotificationController;
 import org.thoughtcrime.securesms.util.StorageUtil;
 import org.thoughtcrime.securesms.util.StreamUtil;
 import org.thoughtcrime.securesms.util.Util;
+import org.thoughtcrime.securesms.util.ViewUtil;
 import org.thoughtcrime.securesms.util.views.ProgressDialog;
 
 import java.io.File;
@@ -62,6 +63,9 @@ public class WelcomeActivity extends BaseActionBarActivity implements DcEventCen
         super.onCreate(bundle);
         setContentView(R.layout.welcome_activity);
 
+        // add padding to avoid content hidden behind system bars
+        ViewUtil.applyWindowInsets(findViewById(R.id.content_container));
+
         Button signUpButton = findViewById(R.id.signup_button);
         Button signInButton = findViewById(R.id.signin_button);
 
@@ -96,7 +100,6 @@ public class WelcomeActivity extends BaseActionBarActivity implements DcEventCen
         boolean canGoBack = AccountManager.getInstance().canRollbackAccountCreation(this);
         supportActionBar.setDisplayHomeAsUpEnabled(canGoBack);
         getSupportActionBar().setTitle(canGoBack? R.string.add_account : R.string.welcome_desktop);
-        getSupportActionBar().setElevation(0); // TODO: use custom toolbar instead
     }
 
     private void registerForEvents() {

src/main/res/layout/welcome_activity.xml

@@ -1,19 +1,19 @@
 <?xml version="1.0" encoding="utf-8"?>
-<RelativeLayout
+<FrameLayout
     xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
-    android:background="?attr/colorPrimary"
-    android:fitsSystemWindows="true"
     android:layout_width="match_parent"
-    android:layout_height="match_parent">
+    android:layout_height="match_parent"
+    tools:context=".WelcomeActivity">
+
+  <include layout="@layout/status_bar_background"/>
 
 <LinearLayout
+    android:id="@+id/content_container"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:orientation="vertical"
-    android:gravity="center_horizontal"
-    android:background="?android:attr/windowBackground"
-    tools:context=".WelcomeActivity">
+    android:gravity="center_horizontal">
 
     <androidx.legacy.widget.Space
         android:layout_weight="3"
@@ -79,4 +79,4 @@
 
 </LinearLayout>
 
-</RelativeLayout>
+</FrameLayout>