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   // Marks all types of favicon for the page as being out of date.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

[sky, 2011/11/16 17:26:00]

Clarify this clones all icons, not just the favicon.

[groby-ooo-7-16, 2011/11/17 00:37:55]

Done.

+  // |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);

[sky, 2011/11/16 17:26:00]

This is worrisome. There's nothing stopping someone from doing something like
CloneFavicon('evil.com', 'good.com'), which we wouldn't want. Could we restrict
this to the same domain? so that you only get to change the path?

[groby-ooo-7-16, 2011/11/17 00:37:55]

I'm confused - how is that any more of a security risk than e.g. allowing a call
to SetFavicon? This is chrome-internal code - if an attacker can call that
directly, security is compromised anyways?

(Added anyways, just in case ;)

[sky, 2011/11/17 04:49:01]

I wasn't worried about the attack risk (as you say, this is chrome code), but
more so of someone accidentally using the API for a case we don't need to
support nor want to support.

+
   // 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.