Add icon to the Data Saver main menu footer and update to spec

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

Index: chrome/android/java/res/drawable/data_reduction_main_menu_icon.xml
diff --git a/chrome/android/java/res/drawable/data_reduction_main_menu_icon.xml b/chrome/android/java/res/drawable/data_reduction_main_menu_icon.xml
new file mode 100644
index 0000000000000000000000000000000000000000..4687a13153a138d4a6d790329f4753b9575b8424
--- /dev/null
+++ b/chrome/android/java/res/drawable/data_reduction_main_menu_icon.xml
@@ -0,0 +1,13 @@
+<?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. -->
+
+<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
+    <item
+        android:id="@+id/main_menu_chart" 
+        android:drawable="@drawable/data_reduction_main_menu_chart"
+        android:layout_gravity="bottom"

[Ted C, 2017/04/10 16:48:48]

I "think" this would need to be android:gravity="bottom", but I don't believe
you need this.

[megjablon, 2017/04/10 18:00:42]

See below

+        android:top="8dp" />

[Ted C, 2017/04/10 16:48:48]

if you did android:bottom="0dp", would that work instead of giving a top offset?

[megjablon, 2017/04/10 18:00:42]

Setting bottom offset doesn't work. The layer-list stretches the item to fill
the space, so this still allows the graph to be drawn to the top.

Just found this in the developer guide:

"All drawable items are scaled to fit the size of the containing View, by
default. Thus, placing your images in a layer list at different positions might
increase the size of the View and some images scale as appropriate. To avoid
scaling items in the list, use a <bitmap> element inside the <item> element to
specify the drawable and define the gravity to something that does not scale,
such as "center"."

https://developer.android.com/guide/topics/resources/drawable-resource.html#L...

So I moved it into a bitmap.

+    <item android:drawable="@drawable/data_reduction_main_menu_chart_base" />
+</layer-list>