Show the image header for the Context Menu

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

Index: chrome/android/java/res/drawable/checkerboard_background.xml
diff --git a/chrome/android/java/res/drawable/checkerboard_background.xml b/chrome/android/java/res/drawable/checkerboard_background.xml
new file mode 100644
index 0000000000000000000000000000000000000000..0acba2c11a919c050c925654a67b006a170e2e3b
--- /dev/null
+++ b/chrome/android/java/res/drawable/checkerboard_background.xml
@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright 2017 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. -->

[Theresa, 2017/03/27 18:28:26]

nit: add a blank line after the Copyright.

[JJ, 2017/03/27 20:47:12]

Done.

+<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
+    <item>
+        <shape android:shape="rectangle">
+            <solid android:color="#FFFFFF" />

[Theresa, 2017/03/27 18:28:26]

nit: @android:color/white

[JJ, 2017/03/27 20:47:12]

Done.

+            <size android:height="10dp" android:width="10dp"/>
+        </shape>
+    </item>
+    <item android:top="0dp" android:left="10dp">
+        <shape android:shape="rectangle">
+            <solid android:color="#EEE"/>

[Theresa, 2017/03/27 18:28:26]

nit: Let's define this as google_grey_200 in colors.xml.

[JJ, 2017/03/27 20:47:12]

Done.

+            <size android:height="10dp" android:width="10dp"/>
+        </shape>
+    </item>
+    <item android:top="10dp" android:left="0dp">
+        <shape android:shape="rectangle">
+            <solid android:color="#EEE"/>
+            <size android:height="10dp" android:width="10dp"/>
+        </shape>
+    </item>
+    <item android:top="10dp" android:left="10dp">
+        <shape android:shape="rectangle">
+            <solid android:color="#FFFFFF" />
+            <size android:height="10dp" android:width="10dp"/>
+        </shape>
+    </item>
+</layer-list>