Switch FaviconTabHelper to use WebContentsUserData.

chrome/browser/ui/cocoa/tab_contents/favicon_util_mac.mm

Index: chrome/browser/ui/cocoa/tab_contents/favicon_util_mac.mm
diff --git a/chrome/browser/ui/cocoa/tab_contents/favicon_util_mac.mm b/chrome/browser/ui/cocoa/tab_contents/favicon_util_mac.mm
index 8112860088dfcf58394fdecb1465fd962367f83a..719a60245526601ed35c5cc29c805897048d6433 100644
--- a/chrome/browser/ui/cocoa/tab_contents/favicon_util_mac.mm
+++ b/chrome/browser/ui/cocoa/tab_contents/favicon_util_mac.mm
@@ -12,8 +12,11 @@
 namespace mac {
 
 NSImage* FaviconForTabContents(TabContents* contents) {
-  if (contents && contents->favicon_tab_helper()->FaviconIsValid()) {
-    NSImage* image = contents->favicon_tab_helper()->GetFavicon().AsNSImage();
+  FaviconTabHelper* favicon_tab_helper =
+      contents ? FaviconTabHelper::FromWebContents(contents->web_contents())

[stevenjb, 2012/10/01 17:56:51]

This seems like a common enough pattern that it would make sense to have a
::FromTabContents. Or would that be difficult/awkward?

[Avi (use Gerrit), 2012/10/01 19:23:57]

I'm on a quest to kill TabContents (see the bug linked from this CL). Adding any
more use of TabContents would be counterproductive.

[stevenjb, 2012/10/01 19:31:46]

Fair enough.

+               : NULL;
+  if (favicon_tab_helper && favicon_tab_helper->FaviconIsValid()) {
+    NSImage* image = favicon_tab_helper->GetFavicon().AsNSImage();
     // The |image| could be nil if the bitmap is null. In that case, fallback
     // to the default image.
     if (image) {