VrShell: implement insecure content warning display

ui/webui/resources/webui_resources.grd

Index: ui/webui/resources/webui_resources.grd
diff --git a/ui/webui/resources/webui_resources.grd b/ui/webui/resources/webui_resources.grd
index 16c90e21cd6db8775249ad16b2c9e78196891569..2a811b5a478bfff2dbb6293852c1962c829c16bc 100644
--- a/ui/webui/resources/webui_resources.grd
+++ b/ui/webui/resources/webui_resources.grd
@@ -200,6 +200,10 @@ without changes to the corresponding grd file. -->
       <if expr="chromeos">
         <part file="cr_elements_images_chromeos.grdp" />
       </if>
+      <if expr="enable_vr_shell">
+        <include name="IDR_WEBUI_IMAGES_I_CIRCLE"

[Dan Beam, 2016/10/03 20:30:59]

btw, you only need to add something to this file if you address it via
chrome://theme/IDR_WEBUI_IMAGES_I_CIRCLE or something or other.  i don't see you
doing that in this CL, so you probably can revert this file.

[klausw, 2016/10/03 21:28:19]

Thanks, removed.

+                 file="images/i_circle.svg" type="BINDATA" />
+      </if>
     </includes>
     <structures>
       <structure name="IDR_WEBUI_CSS_ACTION_LINK"