Get main frame and subframe AppCache loads to work.

content/browser/appcache/appcache_storage.h

Index: content/browser/appcache/appcache_storage.h
diff --git a/content/browser/appcache/appcache_storage.h b/content/browser/appcache/appcache_storage.h
index d01de85163296453f29771396e2ddbf1c1b56122..bda976fc83e486d06becc478ceec1740d5f3fd27 100644
--- a/content/browser/appcache/appcache_storage.h
+++ b/content/browser/appcache/appcache_storage.h
@@ -194,6 +194,9 @@ class CONTENT_EXPORT AppCacheStorage {
   virtual void DeleteResponses(const GURL& manifest_url,
                                const std::vector<int64_t>& response_ids) = 0;
 
+  // Returns true if the AppCacheStorage instance is initialized.
+  virtual bool IsInitialized() = 0;
+
   // Generates unique storage ids for different object types.
   int64_t NewCacheId() { return ++last_cache_id_; }
   int64_t NewGroupId() { return ++last_group_id_; }