Add support for 4-item AppMenu row.

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

Index: chrome/android/java/res/layout/four_button_menu_item.xml
diff --git a/chrome/android/java/res/layout/three_button_menu_item.xml b/chrome/android/java/res/layout/four_button_menu_item.xml
similarity index 77%
copy from chrome/android/java/res/layout/three_button_menu_item.xml
copy to chrome/android/java/res/layout/four_button_menu_item.xml
index ebc73532fb5ffdd57875b4a25612b9058e67aefe..abe580b6b6db6fb5792016a511b40fb36fa66dd1 100644
--- a/chrome/android/java/res/layout/three_button_menu_item.xml
+++ b/chrome/android/java/res/layout/four_button_menu_item.xml
@@ -43,5 +43,18 @@
         android:layout_weight="1"
         android:background="?android:attr/selectableItemBackground"
         android:scaleType="center" />
+    
+    <View
+        android:layout_width="1dp"
+        android:layout_height="?android:attr/listPreferredItemHeightSmall"
+        android:background="?android:attr/listDivider" />
+
+    <ImageButton
+        android:id="@+id/button_four"
+        android:layout_width="wrap_content"
+        android:layout_height="match_parent"
+        android:layout_weight="1"
+        android:background="?android:attr/selectableItemBackground"
+        android:scaleType="center" />
 
 </LinearLayout>