ServiceWorker: Migrate the script cache backend from BlockFile to Simple

content/browser/appcache/appcache_disk_cache.h

Index: content/browser/appcache/appcache_disk_cache.h
diff --git a/content/browser/appcache/appcache_disk_cache.h b/content/browser/appcache/appcache_disk_cache.h
index 6107f5b6b26f767d2a775ce8b1aa1a5d679ce888..98ac3c0a69f3a29ae14e650a0c65f8ea144d52d7 100644
--- a/content/browser/appcache/appcache_disk_cache.h
+++ b/content/browser/appcache/appcache_disk_cache.h
@@ -52,6 +52,10 @@ class CONTENT_EXPORT AppCacheDiskCache
                 const net::CompletionCallback& callback) override;
   int DoomEntry(int64 key, const net::CompletionCallback& callback) override;
 
+  void set_is_waiting_to_initialize(bool is_waiting_to_initialize) {
+    is_waiting_to_initialize_ = is_waiting_to_initialize;
+  }
+
  protected:
   explicit AppCacheDiskCache(bool use_simple_cache);
   disk_cache::Backend* disk_cache() { return disk_cache_.get(); }
@@ -89,9 +93,10 @@ class CONTENT_EXPORT AppCacheDiskCache
   typedef std::set<ActiveCall*> ActiveCalls;
   typedef std::set<EntryImpl*> OpenEntries;
 
-  bool is_initializing() const {
-    return create_backend_callback_.get() != NULL;
+  bool is_initializing_or_waiting_to_initialize() const {
+    return create_backend_callback_.get() != NULL || is_waiting_to_initialize_;
   }
+
   int Init(net::CacheType cache_type,
            const base::FilePath& directory,
            int cache_size,
@@ -104,6 +109,7 @@ class CONTENT_EXPORT AppCacheDiskCache
 
   bool use_simple_cache_;
   bool is_disabled_;
+  bool is_waiting_to_initialize_;
   net::CompletionCallback init_callback_;
   scoped_refptr<CreateBackendCallbackShim> create_backend_callback_;
   PendingCalls pending_calls_;