Back button for landing activities.

res/drawable/ic_baseline_arrow_back_24.xml

@@ -0,0 +1,10 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24"
+    android:tint="?attr/colorControlNormal">
+  <path
+      android:fillColor="@android:color/white"
+      android:pathData="M20,11H7.83l5.59,-5.59L12,4l-8,8 8,8 1.41,-1.41L7.83,13H20v-2z"/>
+</vector>

res/layout/session_logo_action_bar_content.xml

@@ -0,0 +1,32 @@
+<?xml version="1.0" encoding="utf-8"?>
+<RelativeLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="?actionBarSize">
+
+    <ImageView
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_centerInParent="true"
+        android:src="@drawable/session_logo"/>
+
+    <FrameLayout
+        android:id="@+id/back_button"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_centerVertical="true"
+        android:layout_margin="@dimen/small_spacing"
+        android:padding="@dimen/small_spacing"
+        android:background="@drawable/circle_touch_highlight_background"
+        android:clickable="true"
+        android:focusable="true">
+
+        <ImageView
+            android:layout_width="24dp"
+            android:layout_height="24dp"
+            android:src="@drawable/ic_baseline_arrow_back_24"
+            android:alpha="0.5"/>
+
+    </FrameLayout>
+
+</RelativeLayout>

src/org/thoughtcrime/securesms/loki/activities/LandingActivity.kt

@@ -40,7 +40,7 @@ class LandingActivity : BaseActionBarActivity(), LinkDeviceSlaveModeDialogDelega
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_landing)
-        setUpActionBarSessionLogo()
+        setUpActionBarSessionLogo(true)
         fakeChatView.startAnimating()
         registerButton.setOnClickListener { register() }
         restoreButton.setOnClickListener { restore() }

src/org/thoughtcrime/securesms/loki/utilities/ActivityUtilities.kt

@@ -1,24 +1,36 @@
 package org.thoughtcrime.securesms.loki.utilities
 
 import android.content.Intent
-import androidx.appcompat.app.ActionBar
+import android.view.View
 import androidx.appcompat.app.AppCompatActivity
-import android.view.Gravity
-import android.widget.ImageView
-import android.widget.RelativeLayout
+import androidx.appcompat.widget.Toolbar
 import network.loki.messenger.R
+import org.thoughtcrime.securesms.BaseActionBarActivity
 
-fun AppCompatActivity.setUpActionBarSessionLogo() {
-    supportActionBar!!.setDisplayShowHomeEnabled(false)
-    supportActionBar!!.setDisplayShowTitleEnabled(false)
-    val logoImageView = ImageView(this)
-    logoImageView.setImageResource(R.drawable.session_logo)
-    val logoImageViewContainer = RelativeLayout(this)
-    logoImageViewContainer.addView(logoImageView)
-    logoImageViewContainer.gravity = Gravity.CENTER
-    val logoImageViewContainerLayoutParams = ActionBar.LayoutParams(ActionBar.LayoutParams.MATCH_PARENT, ActionBar.LayoutParams.WRAP_CONTENT)
-    supportActionBar!!.setCustomView(logoImageViewContainer, logoImageViewContainerLayoutParams)
-    supportActionBar!!.setDisplayShowCustomEnabled(true)
+fun BaseActionBarActivity.setUpActionBarSessionLogo(hideBackButton: Boolean = false) {
+    val actionbar = supportActionBar!!
+
+    actionbar.setDisplayShowHomeEnabled(false)
+    actionbar.setDisplayShowTitleEnabled(false)
+    actionbar.setDisplayHomeAsUpEnabled(false)
+    actionbar.setHomeButtonEnabled(false)
+
+    actionbar.setCustomView(R.layout.session_logo_action_bar_content)
+    actionbar.setDisplayShowCustomEnabled(true)
+
+    val rootView: Toolbar = actionbar.customView!!.parent as Toolbar
+    rootView.setPadding(0,0,0,0)
+    rootView.setContentInsetsAbsolute(0,0);
+
+    val backButton = actionbar.customView!!.findViewById<View>(R.id.back_button)
+    if (hideBackButton) {
+        backButton.visibility = View.GONE
+    } else {
+        backButton.visibility = View.VISIBLE
+        backButton.setOnClickListener {
+            onSupportNavigateUp()
+        }
+    }
 }
 
 val AppCompatActivity.defaultSessionRequestCode: Int