For #11903: fix custom tab private gradient

app/src/main/java/org/mozilla/fenix/customtabs/CustomTabsIntegration.kt

@@ -5,7 +5,7 @@
 package org.mozilla.fenix.customtabs
 
 import android.app.Activity
-import androidx.appcompat.content.res.AppCompatResources
+import androidx.appcompat.content.res.AppCompatResources.getDrawable
 import mozilla.components.browser.session.SessionManager
 import mozilla.components.browser.toolbar.BrowserToolbar
 import mozilla.components.browser.toolbar.display.DisplayToolbar
@@ -30,16 +30,13 @@ class CustomTabsIntegration(
         // Remove toolbar shadow
         toolbar.elevation = 0f
 
-        val uncoloredEtpShield = AppCompatResources.getDrawable(
-            activity,
-            R.drawable.ic_tracking_protection_enabled
-        )!!
+        val uncoloredEtpShield = getDrawable(activity, R.drawable.ic_tracking_protection_enabled)!!
 
         toolbar.display.icons = toolbar.display.icons.copy(
             // Custom private tab backgrounds have bad contrast against the colored shield
             trackingProtectionTrackersBlocked = uncoloredEtpShield,
             trackingProtectionNothingBlocked = uncoloredEtpShield,
-            trackingProtectionException = AppCompatResources.getDrawable(
+            trackingProtectionException = getDrawable(
                 activity,
                 R.drawable.ic_tracking_protection_disabled
             )!!
@@ -70,10 +67,7 @@ class CustomTabsIntegration(
                 )
             }
 
-            toolbar.background = AppCompatResources.getDrawable(
-                activity,
-                R.drawable.toolbar_background
-            )
+            toolbar.background = getDrawable(activity, R.drawable.toolbar_background_private)
         }
     }
 

app/src/main/res/drawable/toolbar_background_private.xml

@@ -0,0 +1,22 @@
+<?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/. -->
+<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
+    <item>
+        <shape android:shape="rectangle">
+             <gradient
+                android:angle="45"
+                android:startColor="@color/toolbar_start_gradient_private_theme"
+                android:centerColor="@color/toolbar_center_gradient_private_theme"
+                android:endColor="@color/toolbar_end_gradient_private_theme"
+                android:type="linear" />
+        </shape>
+    </item>
+    <item android:gravity="top">
+        <shape android:shape="rectangle">
+            <size android:height="1dp" />
+            <solid android:color="@color/neutral_faded_private_theme" />
+        </shape>
+    </item>
+</layer-list>