Provide assumed favicon for intents if service provider page was never visited.

chrome/browser/favicon/favicon_service.h

Index: chrome/browser/favicon/favicon_service.h
diff --git a/chrome/browser/favicon/favicon_service.h b/chrome/browser/favicon/favicon_service.h
index 4fb313b3531c6fe5beed118976ce5eeee230f303..252ca448decef7984e83d81ba5ff8a5b1e7d8504 100644
--- a/chrome/browser/favicon/favicon_service.h
+++ b/chrome/browser/favicon/favicon_service.h
@@ -82,6 +82,13 @@ class FaviconService : public CancelableRequestProvider {
   // Marks all types of favicon for the page as being out of date.
   void SetFaviconOutOfDateForPage(const GURL& page_url);
 
+  // Clone a favicon from an existing page. This associates the favicon from
+  // |old_page_url| with |new_page_url|, provided |new_page_url| has no
+  // recorded association.
+  // Needed if you want to declare favicons (tentatively) in advance, before a
+  // page is ever visited.
+  void CloneFavicon(const GURL& old_page_url, const GURL& new_page_url);
+
   // Allows the importer to set many favicons for many pages at once. The pages
   // must exist, any favicon sets for unknown pages will be discarded. Existing
   // favicons will not be overwritten.