Make the ShortcutHelper toast instead of send the user home for web app banners

chrome/android/java/strings/android_chrome_strings.grd

 <?xml version="1.0" encoding="UTF-8"?>
 <grit current_release="1" latest_public_release="0">
   <outputs>
     <output filename="values-am/android_chrome_strings.xml" lang="am" type="android" />
     <output filename="values-ar/android_chrome_strings.xml" lang="ar" type="android" />
     <output filename="values-bg/android_chrome_strings.xml" lang="bg" type="android" />
     <output filename="values-ca/android_chrome_strings.xml" lang="ca" type="android" />
     <output filename="values-cs/android_chrome_strings.xml" lang="cs" type="android" />
     <output filename="values-da/android_chrome_strings.xml" lang="da" type="android" />
     <output filename="values-de/android_chrome_strings.xml" lang="de" type="android" />
@@ skipping 951 matching lines @@
       <!-- Add to Homescreen strings -->
       <message name="IDS_ADD" desc="Title for Add button [CHAR-LIMIT=20]">
         Add
       </message>
       <message name="IDS_ADD_TO_HOMESCREEN_TITLE" desc="Edit text title for Add to homescreen dialog [CHAR-LIMIT=30]">
         Title
       </message>
       <message name="IDS_MENU_ADD_TO_HOMESCREEN" desc="Menu item for adding a shortcut to the homescreen. [CHAR-LIMIT=27]">
         Add to homescreen
       </message>
+      <message name="IDS_ADDED_TO_HOMESCREEN" desc="Indicates that the current site was added to the user's homescreen.">
+        This site was added to your homescreen

[felt, 2015/02/18 22:03:45]

would it make more sense to specify the origin ("foo.com was added to your
homescreen") instead of saying "This site"? (up to you: a suggestion, not a
security requirement)

+      </message>
 
       <!-- WebsiteSettingsPopup (PageInfo dialog) -->
       <message name="IDS_PAGE_INFO_COPY_URL_BUTTON" desc="Text in the button that copies the URL to the clipboard.">
         Copy URL
       </message>
       <message name="IDS_PAGE_INFO_SITE_SETTINGS_BUTTON" desc="Text in the button that opens a website's Site Settings from the Page Info dialog.">
         Site Settings
       </message>
       <message name="IDS_PAGE_INFO_PERMISSION_ALLOW" desc="The label used in the permissions dropdowns in the Page Info dialog on mobile for the option that grants a permission.">
         Allow
@@ skipping 119 matching lines @@
       <message name="IDS_CARD_UNMASK_INPUT_HINT" desc="Hint text for an input field containing the user's credit card CVC (card verification code).">
         CVC
       </message>
       <message name="IDS_AUTOFILL_CARD_UNMASK_PROMPT_STORE_LOCALLY" desc="Checkbox text that permits a user to skip past this dialog next time this credit card is used on this device.">
         Don't ask again for this card
       </message>
 
     </messages>
   </release>
 </grit>