Switch BookmarkTabHelper to use WebContentsUserData.

chrome/browser/tab_contents/web_drag_bookmark_handler_gtk.h

Index: chrome/browser/tab_contents/web_drag_bookmark_handler_gtk.h
diff --git a/chrome/browser/tab_contents/web_drag_bookmark_handler_gtk.h b/chrome/browser/tab_contents/web_drag_bookmark_handler_gtk.h
index 72a052da82257f542246e74b95826f098bf8327c..f144340d350ed343f37672e5817dd9358b8e28cc 100644
--- a/chrome/browser/tab_contents/web_drag_bookmark_handler_gtk.h
+++ b/chrome/browser/tab_contents/web_drag_bookmark_handler_gtk.h
@@ -9,7 +9,11 @@
 #include "chrome/browser/bookmarks/bookmark_node_data.h"
 #include "content/public/browser/web_drag_dest_delegate.h"
 
-class TabContents;
+class BookmarkTabHelper;
+
+namespace content {
+class WebContents;
+}
 
 // Chrome needs to intercept content drag events so it can dispatch them to the
 // bookmarks and extensions system.
@@ -30,10 +34,12 @@ class WebDragBookmarkHandlerGtk : public content::WebDragDestDelegate {
   virtual void OnDragLeave() OVERRIDE;
 
  private:
-  // The TabContents.
-  // Weak reference; may be NULL if the contents aren't contained in a
-  // TabContents (e.g. WebUI dialogs).
-  TabContents* tab_;
+  // The BookmarkTabHelper.
+  // Weak reference; may be NULL if the contents don't have a
+  // BookmarkTabHelper (e.g. WebUI dialogs).
+  BookmarkTabHelper* bookmark_tab_helper_;
+
+  content::WebContents* web_contents_;
 
   // The bookmark data for the current tab. This will be empty if there is not
   // a native bookmark drag (or we haven't gotten the data from the source yet).