[Explore Sites]: Remove the special button background snowflake

Bug: 856172
Change-Id: I19d5e6052fb394aba40bde96bfa40762cc7e4e44
Reviewed-on: https://chromium-review.googlesource.com/1152100
Commit-Queue: Cathy Li <chili@chromium.org>
Reviewed-by: Theresa <twellington@chromium.org>
Reviewed-by: Justin DeWitt <dewittj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#578748}

chrome/android/java/res/drawable/explore_sites_button_background.xml

-<?xml version="1.0" encoding="utf-8"?>
-
-<!-- Copyright 2018 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.
--->
-
-<!-- TODO(chili): Remove after explore sites prototype, or restyle to generally accepted style -->
-<shape xmlns:android="http://schemas.android.com/apk/res/android"
-        android:shape="rectangle">
-    <solid android:color="@color/light_background_color" />
-    <corners android:radius="4dp" />
-    <stroke android:width="1dp" android:color="@color/google_grey_300" />
-</shape>

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

@@ -28,7 +28,6 @@
         android:orientation="horizontal" />
 
     <Button
-        style="@style/ExploreSitesAction"
         android:id="@+id/explore_sites_more_button"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"

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

@@ -794,10 +794,4 @@
       <item name="android:paddingStart">?android:attr/listPreferredItemPaddingStart</item>
       <item name="android:paddingEnd">?android:attr/listPreferredItemPaddingEnd</item>
     </style>
-
-    <!-- Explore sites section -->
-    <style name="ExploreSitesAction" parent="ButtonCompatBorderless">
-        <item name="android:textAppearance">@style/BlueLink2</item>
-        <item name="android:background">@drawable/explore_sites_button_background</item>
-    </style>
 </resources>

chrome/android/java/res/values-v21/styles.xml

@@ -117,12 +117,4 @@
              half is way brighter than the bottom), so we use our own. -->
         <item name="android:textCursorDrawable">@drawable/text_cursor_lowend</item>
     </style>
-
-    <!-- Explore sites section -->
-    <style name="ExploreSitesAction" parent="ButtonCompatBorderless">
-        <item name="android:textAppearance">@style/BlueLink2</item>
-        <item name="android:background">@drawable/explore_sites_button_background</item>
-        <!-- API 21 introduces state list animation. This will remove the auto-shadow -->
-        <item name="android:stateListAnimator">@null</item>
-    </style>
 </resources>