Change navigation bar back button color in xamarin android

Hi everyone, In my application default back button color is white. I need to change that back button color to black. I am tried so many post's for changing back button of navigation bar but no luck. Can you please suggest any idea. Here is my theme design.

style.axml:

 <resources>
   <style name="MyTheme" parent="MyTheme.Base">
   </style>
   <style name="Theme.Splash" parent="@android:style/Theme.NoTitleBar.Fullscreen">         
    <item name="android:windowBackground">@drawable/Splash</item>
    <item name="android:windowNoTitle">true</item>
   </style>
   <style name="MyTheme.Base" parent="Theme.AppCompat.Light.NoActionBar">
     <item name="colorPrimary">@color/primary</item>
    <item name="colorPrimaryDark">@color/primaryDark</item>   
    <item name="colorAccent">@color/accent</item>
    <item name="android:windowBackground">@color/window_background</item>
   </style>
 </resources> 

styles.xml:

<resources>
  <style name="MainTheme" parent="MainTheme.Base">
  </style>     
  <style name="MainTheme.Base" parent="Theme.AppCompat.Light.DarkActionBar">      
    <item name="windowNoTitle">true</item>   
    <item name="windowActionBar">false</item>    
    <item name="colorPrimary">#fcce47</item>    
    <item name="colorPrimaryDark">#000000</item>    
    <item name="colorAccent">#000000</item>    
    <item name="windowActionModeOverlay">true</item>
    <item name="android:textCursorDrawable">@null</item>
    <item name="android:datePickerDialogTheme">@style/AppCompatDialogStyle</item>
  </style>

  <style name="AppCompatDialogStyle" parent="Theme.AppCompat.Light.Dialog">
     <item name="colorAccent">#FF4081</item>
  </style>
</resources>