Add empty view for empty groups

Bug 28982874

Change-Id: I757651e3fd2897d65609ab233722160e0b267b01
diff --git a/res/values/colors.xml b/res/values/colors.xml
index 8fa0e0d..d71363d 100644
--- a/res/values/colors.xml
+++ b/res/values/colors.xml
@@ -77,4 +77,8 @@
 
     <!-- Color of background of disabled link contacts button, 15% black. -->
     <color name="disabled_button_background">#26000000</color>
+
+    <!-- Color of background of all empty states. -->
+    <color name="empty_state_background">#efefef</color>
+
 </resources>