Fix inconsistent and incorrect Roboto Medium usage

chrome/android/java/res/layout/contextual_search_peek_promo_text_view.xml

 <?xml version="1.0" encoding="utf-8"?>
 <!--
    Copyright 2015 The Chromium Authors. All rights reserved.
 
    Use of this source code is governed by a BSD-style license that can be
    found in the LICENSE file.
 -->
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
               android:id="@+id/contextual_search_peek_promo_text_view"
               android:layout_width="match_parent"
               android:layout_height="wrap_content"
               android:orientation="horizontal"
               android:paddingStart="@dimen/contextual_search_peek_promo_padding"
               android:paddingEnd="@dimen/contextual_search_peek_promo_padding"
               android:visibility="invisible">
     <TextView
+        style="@style/RobotoMediumStyle"
         android:id="@+id/contextual_search_peek_promo_new"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_marginEnd="@dimen/contextual_search_peek_promo_padding"
         android:background="@drawable/contextual_search_peek_promo_new_background"
-        android:fontFamily="sans-serif-medium"
         android:text="@string/contextual_search_peek_promo_new"
         android:textAllCaps="true"
         android:textColor="@color/light_active_color"
         android:textSize="14sp"
         />
     <!-- TODO(pedrosimonetti): Find a better layout for handling multiline text -->
     <TextView
         android:id="@+id/contextual_search_peek_promo_text"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:fontFamily="sans-serif"
         android:text="@string/contextual_search_peek_promo_text"
         android:textColor="#FFF"
         android:textSize="14sp"
         />
 </LinearLayout>