Replace Google Search Action on Navication Bar

AndroidManifest.xml

<!-- target activity -->
<activity android:name="...">
	<meta-data 
        	android:name="com.android.systemui.action_assist_icon"
        	android:resource="@drawable/ic_assist"/>
        	
	<intent-filter>
        	<action android:name="android.intent.action.ASSIST"/>
                <category android:name="android.intent.category.DEFAULT"/>
        </intent-filter>
</activity>

ic_assist.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android"
          android:enterFadeDuration="@integer/config_miniAnimTime"
          android:exitFadeDuration="@integer/config_miniAnimTime">

    <item android:state_active="true" android:drawable="@drawable/ic_assist_active"/>
    <item android:drawable="@drawable/ic_assist_normal"/>
</selector>