For 11616: removed black flicker with placeholder animation (#11796)

Increasing duration removed second "light" flicker

app/src/main/res/anim/placeholder_animation.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<translate
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:fromXDelta="0"
+    android:toXDelta="0"
+    android:duration="900" />

app/src/main/res/values/styles.xml

@@ -20,6 +20,7 @@
         <item name="alertDialogStyle">@style/DialogStyleNormal</item>
         <item name="alertDialogTheme">@style/DialogStyleNormal</item>
         <item name="android:windowEnableSplitTouch">false</item>
+        <item name="android:navigationBarColor">@android:color/transparent</item>
         <item name="android:splitMotionEvents">false</item>
 
         <item name="mozacInputLayoutErrorTextColor"

app/src/migration/java/org/mozilla/fenix/MigrationDecisionActivity.kt

@@ -39,6 +39,6 @@ class MigrationDecisionActivity : Activity() {
         // and then we switch to the actual activity without an animation. This visually looks like
         // a faster start than launching this activity invisibly and switching to the actual
         // activity after that.
-        overridePendingTransition(0, 0)
+        overridePendingTransition(0, R.anim.placeholder_animation)
     }
 }