Use copies of canned browsing data helpers to populate the cookies tree model.

chrome/browser/browsing_data_appcache_helper.h

Index: chrome/browser/browsing_data_appcache_helper.h
diff --git a/chrome/browser/browsing_data_appcache_helper.h b/chrome/browser/browsing_data_appcache_helper.h
index 38eaed488bb43263205d4af56753aca08bd4aa54..b66b9d2b0767f607fa0d19aedf6d90a58ad1b4f2 100644
--- a/chrome/browser/browsing_data_appcache_helper.h
+++ b/chrome/browser/browsing_data_appcache_helper.h
@@ -56,6 +56,11 @@ class CannedBrowsingDataAppCacheHelper : public BrowsingDataAppCacheHelper {
  public:
   explicit CannedBrowsingDataAppCacheHelper(Profile* profile);
 
+  // Return a copy of the appcache helper. Only one consumer can use the
+  // StartFetching method at a time, so we need to create a copy of the helper
+  // everytime we instantiate a cookies tree model for it.
+  CannedBrowsingDataAppCacheHelper* Clone();
+
   // Add an appcache to the set of canned caches that is returned by this
   // helper.
   void AddAppCache(const GURL& manifest_url);
@@ -73,6 +78,8 @@ class CannedBrowsingDataAppCacheHelper : public BrowsingDataAppCacheHelper {
  private:
   virtual ~CannedBrowsingDataAppCacheHelper();
 
+  Profile* profile_;
+
   DISALLOW_COPY_AND_ASSIGN(CannedBrowsingDataAppCacheHelper);
 };