Add an experimental search widget

chrome/android/java/res/values-v17/styles.xml

 <?xml version="1.0" encoding="utf-8"?>
 <!-- Copyright 2014 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. -->
 
 <resources xmlns:tools="http://schemas.android.com/tools">
     <!-- Q: Why put style resources under values-v17/ ?
          A: Problem:
             1. paddingStart causes a crash on Galaxy Tab&Note b/8351339.
             2. So we wrote a build script(generate_v14_compatible_resources.py) to convert
@@ skipping 55 matching lines @@
     </style>
     <style name="WebappSplashScreenTextTheme">
         <item name="android:textSize">24sp</item>
         <item name="android:ellipsize">end</item>
         <item name="android:textColor">@color/default_text_color</item>
         <item name="android:gravity">center</item>
         <item name="android:fontFamily">sans-serif-condensed</item>
         <item name="android:maxLines">2</item>
     </style>
 
+    <style name="OverlayTheme" parent="MainTheme">
+      <!-- Using these values will make the Activity translucent.
+           <item name="android:windowIsTranslucent">true</item>
+           <item name="android:windowBackground">@android:color/transparent</item>
+           <item name="android:windowContentOverlay">@null</item>
+           <item name="android:windowNoTitle">true</item>
+      -->
+      <item name="android:windowBackground">@color/light_normal_color</item>
+    </style>
+
     <style name="AlertDialogTheme" parent="Theme.AppCompat.Light.Dialog.Alert">
         <item name="android:textColorHighlight">@color/text_highlight_color</item>
 
         <!--  Overriding AppCompat values -->
         <item name="colorAccent">@color/light_active_color</item>
         <item name="colorControlActivated">@color/light_active_color</item>
         <item name="colorControlNormal">@color/light_normal_color</item>
         <item name="colorPrimary">@color/light_active_color</item>
 
         <!-- Default TintedImageButton tint -->
@@ skipping 580 matching lines @@
         <item name="android:contentDescription">@null</item>
         <item name="android:scaleType">center</item>
         <item name="android:background">@color/light_active_color</item>
     </style>
 
     <!-- Miscellaneous -->
     <style name="BottomSheetContentTitle" parent="TextAppearance.Widget.AppCompat.Toolbar.Title">
         <item name="android:textSize">20sp</item>
     </style>
 </resources>