[WIP] Hack on Blob mojom

content/common/blob.mojom

+// Copyright 2016 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.
+
+// TODO - maybe this mojom should just live in //storage?
+
+module content.mojom;
+
+// Maps to storage::DataElement.
+[Native]
+struct StorageDataElement;
+
+// TODO: de-dupe this and the definition in blob_storage_constants.h
+enum BlobCreationCancelCode {
+  UNKNOWN = 0,
+  OUT_OF_MEMORY = 1,
+  // We couldn't create or write to a file. File system error, like a full disk.
+  FILE_WRITE_FAILED = 2,
+  // The renderer was destroyed while data was in transit.
+  SOURCE_DIED_IN_TRANSIT = 3,
+  // The renderer destructed the blob before it was done transferring, and there
+  // were no outstanding references (no one is waiting to read) to keep the
+  // blob alive.
+  BLOB_DEREFERENCED_WHILE_BUILDING = 4,
+  // A blob that we referenced during construction is broken, or a browser-side
+  // builder tries to build a blob with a blob reference that isn't finished
+  // constructing.
+  REFERENCED_BLOB_BROKEN = 5,
+  LAST = 5,
+};
+
+// TODO
+interface Blob {};
+
+interface BlobFactory {
+  RegisterBlobUUID(string uuid, string content_type, string content_disposition,
+      array<string> referenced_blob_uuids);
+
+  // Builds a new blob.
+  //
+  // The StorageDataElements are used to:
+  // * describe & transport non-memory resources (blobs, files, etc)
+  // * describe the size of memory items
+  // * 'shortcut' transport the memory up to the IPC limit so the browser can use
+  //   it if it's not currently full.
+  // See https://bit.ly/BlobStorageRefactor
+  //
+  // This returns a handle to a Blob interface if successful. Otherwise the
+  // build request was cancelled and |cancel_code| indicates why. If |blob| is
+  // non-null, |cancel_code| is unspecified and should be ignored.
+  BuildBlob(string uuid, string content_type, string content_disposition,
+            array<string> referenced_blob_uuids,
+            array<StorageDataElement> item_descriptions)
+      => (associated Blob? blob, BlobCreationCancelCode cancel_code);
+};