Introducing the WebServiceWorkerCacheStorage.

public/platform/WebServiceWorkerCacheStorage.h

Index: public/platform/WebServiceWorkerCacheStorage.h
diff --git a/public/platform/WebServiceWorkerCacheStorage.h b/public/platform/WebServiceWorkerCacheStorage.h
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index 0000000000000000000000000000000000000000..5a6a2f778a37ccc2276d73f94d7de6ce29728053
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+++ b/public/platform/WebServiceWorkerCacheStorage.h
@@ -0,0 +1,47 @@
+// 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 WebServiceWorkerCacheStorage_h
+#define WebServiceWorkerCacheStorage_h
+
+#include "WebCommon.h"
+#include "public/platform/WebCallbacks.h"
+#include "public/platform/WebString.h"
+#include "public/platform/WebVector.h"
+#include <string>
+#include <vector>
+
+namespace WebCore { class ServiceWorker; }
+
+namespace blink {
+
+// An interface to the CacheStorage API, implemented by the embedder and passed in to blink.
+class WebServiceWorkerCacheStorage {
+public:
+    enum ErrorReason {

[jkarlin, 2014/07/23 12:03:32]

Please add 'CacheStorageErrorNoError' as the first entry to this so that the
caching functions can return an 'OK' error code.

[gavinp, 2014/07/25 07:44:03]

(your name still shows OOO from your vacation...)

I think because the error reason is only provided on callbacks that fail, having
OK here would be a mistake. If it's being extended downstream by someone that's
OK, even if it is annoying to extend an enum.

+        CacheStorageErrorNotImplemented,
+        CacheStorageErrorNotFound,
+        CacheStorageErrorExists,
+        CacheStorageErrorLast = CacheStorageErrorExists

[jkarlin, 2014/07/24 13:20:16]

Please append CacheStorageErrorStorage to the enum for things like backend
failures (e.g., couldn't mkdir).

[gavinp, 2014/07/25 07:44:03]

Tricky decision. I can see the argument; this failure can occur, and why not let
the blink code handle the mapping from all the various types of failures to the
API requirements. In one sense, that's keeping API logic in blink which is good.

On the other hand, why have the WebFoo interfaces include implementation details
from the embedder? Isn't "NotFound" the right return here? Can anyone else chime
in on the right call?

I am kind of inclined to do what Josh is suggesting, add more values here, and
map them into exceptions from the serviceworker spec in CacheStorage.cpp? 

+    };
+
+    typedef WebCallbacks<void, ErrorReason> CacheStorageCallbacks;
+    typedef WebCallbacks<int /* cacheID */, ErrorReason> CacheStorageWithCacheCallbacks;
+    typedef WebCallbacks<WebVector<WebString>, ErrorReason> CacheStorageKeysCallbacks;
+
+    WebServiceWorkerCacheStorage() { }
+    virtual ~WebServiceWorkerCacheStorage() { }
+
+    // Ownership of the CacheStorage*Callbacks methods passes to the WebServiceWorkerCacheStorage
+    // instance, which will delete it after calling onSuccess or onFailure.
+    virtual void dispatchCreate(CacheStorageWithCacheCallbacks*, const WebString& key) = 0;
+    virtual void dispatchRename(CacheStorageCallbacks*, const WebString& oldKey, const WebString& newKey) = 0;
+    virtual void dispatchGet(CacheStorageWithCacheCallbacks*, const WebString& key) = 0;
+    virtual void dispatchDelete(CacheStorageCallbacks*, const WebString& key) = 0;
+    virtual void dispatchKeys(CacheStorageKeysCallbacks*) = 0;
+};
+
+} // namespace blink
+
+#endif // WebServiceWorkerCacheStorage_h