Move ServiceWorkerCache backend creation to a lazy init function.

content/browser/service_worker/service_worker_cache.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_CACHE_H_
 #define CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_CACHE_H_
 
 #include "base/callback.h"
 #include "base/files/file_path.h"
 #include "base/memory/weak_ptr.h"
@@ skipping 41 matching lines @@
       RequestsCallback;
 
   static scoped_ptr<ServiceWorkerCache> CreateMemoryCache(
       net::URLRequestContext* request_context,
       base::WeakPtr<storage::BlobStorageContext> blob_context);
   static scoped_ptr<ServiceWorkerCache> CreatePersistentCache(
       const base::FilePath& path,
       net::URLRequestContext* request_context,
       base::WeakPtr<storage::BlobStorageContext> blob_context);
 
+  // Operations in progress will complete after the cache is deleted but pending
+  // operations (those operations waiting for init to finish) won't.
   virtual ~ServiceWorkerCache();
 
-  // Loads the backend and calls the callback with the result (true for
-  // success). This must be called before member functions that require a
-  // backend are called. The callback will always be called.
-  void CreateBackend(const ErrorCallback& callback);
-
   // Returns ErrorTypeNotFound if not found. The callback will always be called.
   // |request| must remain valid until the callback is called.
   void Match(scoped_ptr<ServiceWorkerFetchRequest> request,
              const ResponseCallback& callback);
 
   // Puts the request and response object in the cache. The response body (if
   // present) is stored in the cache, but not the request body. Returns
   // ErrorTypeOK on success. The callback will always be called. |request| and
   // |response| must remain valid until the callback is called.
   void Put(scoped_ptr<ServiceWorkerFetchRequest> request,
            scoped_ptr<ServiceWorkerResponse> response,
            const ErrorCallback& callback);
 
   // Returns ErrorNotFound if not found. Otherwise deletes and returns
   // ErrorTypeOK. The callback will always be called. |request| must remain
   // valid until the callback is called.
   void Delete(scoped_ptr<ServiceWorkerFetchRequest> request,
               const ErrorCallback& callback);
 
   // TODO(jkarlin): Have keys take an optional ServiceWorkerFetchRequest.
   // Returns ErrorTypeOK and a vector of requests if there are no errors. The
   // callback will always be called.
   void Keys(const RequestsCallback& callback);
 
-  // Call to determine if CreateBackend must be called.
-  bool HasCreatedBackend() const;
-
   void set_backend(scoped_ptr<disk_cache::Backend> backend) {
     backend_ = backend.Pass();
   }
 
   base::WeakPtr<ServiceWorkerCache> AsWeakPtr();
 
  private:
   struct KeysContext;
   typedef std::vector<disk_cache::Entry*> Entries;
 
   ServiceWorkerCache(const base::FilePath& path,
                      net::URLRequestContext* request_context,
                      base::WeakPtr<storage::BlobStorageContext> blob_context);
 
   // Static callbacks for the Keys function.
   static void KeysDidOpenNextEntry(scoped_ptr<KeysContext> keys_context,
                                    int rv);
   static void KeysProcessNextEntry(scoped_ptr<KeysContext> keys_context,
                                    const Entries::iterator& iter);
   static void KeysDidReadHeaders(
       scoped_ptr<KeysContext> keys_context,
       const Entries::iterator& iter,
       scoped_ptr<ServiceWorkerRequestResponseHeaders> headers);
 
+  // Loads the backend and calls the callback with the result (true for
+  // success). The callback will always be called.
+  void CreateBackend(const ErrorCallback& callback);
+
+  void Init(const base::Closure& callback);
+  void InitDone(ErrorType error);
+
   scoped_ptr<disk_cache::Backend> backend_;
   base::FilePath path_;
   net::URLRequestContext* request_context_;
   base::WeakPtr<storage::BlobStorageContext> blob_storage_context_;
+  bool initialized_;
+  std::vector<base::Closure> init_callbacks_;
 
   base::WeakPtrFactory<ServiceWorkerCache> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ServiceWorkerCache);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_CACHE_H_