Add message and Help Center link to the chooser UI

chrome/app/generated_resources.grd

Index: chrome/app/generated_resources.grd
diff --git a/chrome/app/generated_resources.grd b/chrome/app/generated_resources.grd
index 2bde5cb3688c02a1ea67b5bd0076c0da0e00974a..57cf022bd225b7352a7b682e332897c53e426da2 100644
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -14603,6 +14603,10 @@ Please check your email at <ph name="ACCOUNT_EMAIL">$2<ex>jane.doe@gmail.com</ex
       <message name="IDS_CHOOSER_BUBBLE_CANCEL_BUTTON_TEXT" desc="The text that is shown on the cancel button in the chooser popup.">
         Cancel
       </message>
+      <!-- Chooser Bubble Privacy Message Text -->
+      <message name="IDS_CHOOSER_BUBBLE_PRIVACY_MESSAGE_TEXT" desc="The text that is shown on the bottom of the chooser popup.">

[Reilly Grant (use Gerrit), 2016/02/03 18:49:08]

This description doesn't give the translator enough context to understand the
message. Please read this guide for creating good message descriptions:
https://www.chromium.org/developers/design-documents/ui-localization?pli=1#TO...

I suggest, "This text is shown at the bottom of the chooser popup and informs
the user of the privacy implications of the choice they will be making."

[juncai, 2016/02/03 19:05:24]

Done.

+        This site will have access to the selected device and any information the device contains.
+      </message>
     </if>
 
     <if expr="is_android">