[PresentationAPI] Plumbing send(Blob) from PresentationSession IDL to platform/.

Source/modules/presentation/PresentationSession.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 PresentationSession_h
 #define PresentationSession_h
 
 #include "core/events/EventTarget.h"
+#include "core/fileapi/Blob.h"
+#include "core/fileapi/FileError.h"
 #include "core/frame/DOMWindowProperty.h"
 #include "public/platform/modules/presentation/WebPresentationSessionClient.h"
 #include "wtf/text/WTFString.h"
 
 namespace WTF {
 class AtomicString;
 } // namespace WTF
 
 namespace blink {
 
@@ skipping 18 matching lines @@
     virtual ExecutionContext* executionContext() const override;
 
     DECLARE_VIRTUAL_TRACE();
 
     const String id() const { return m_id; }
     const WTF::AtomicString& state() const;
 
     void send(const String& message, ExceptionState&);
     void send(PassRefPtr<DOMArrayBuffer> data, ExceptionState&);
     void send(PassRefPtr<DOMArrayBufferView> data, ExceptionState&);
+    void send(Blob* data, ExceptionState&);
     void close();
 
     DEFINE_ATTRIBUTE_EVENT_LISTENER(message);
     DEFINE_ATTRIBUTE_EVENT_LISTENER(statechange);
 
     // Returns true if and only if the WebPresentationSessionClient represents this session.
     bool matches(WebPresentationSessionClient*) const;
 
     // Notifies the session about its state change.
     void didChangeState(WebPresentationSessionState);
 
     // Notifies the session about new text message.
     void didReceiveTextMessage(const String& message);
 
 private:
+    class BlobLoader;
+    // Blob data items are queued and sent after loading asynchronously.
+    struct Message {
+        Message(PassRefPtr<BlobDataHandle> blobDataHandle)
+            : blobDataHandle(blobDataHandle)
+        {
+        }
+
+        RefPtr<BlobDataHandle> blobDataHandle;
+        // TODO(s.singapati): Currently String and ArrayBuffer data is sent

[mark a. foltz, 2015/05/26 20:41:48]

It looks like the way that WebSocket implements send(Blob) is to:

1. keep the blob handle at the head of the queue & start a BlobLoader
2. blocks further sends
3. when loading is complete, replace the handle with the blob contents
4. resumes the queue

https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...

Can we do something similar here?

[USE s.singapati at gmail.com, 2015/05/27 19:37:51]

Done. One difference is, this patch does not replace the handle with the loaded
blob contents, But sends it immediately, then continue processing the queue.

+        // immediately to the client, but Blob data is loaded as array buffer
+        // asynchrounously and then sent. This makes message sending order
+        // incorrect.
+    };
+
     PresentationSession(LocalFrame*, const String& id, const String& url);
 
     // Returns the |PresentationController| object associated with the frame
     // |Presentation| corresponds to. Can return |nullptr| if the frame is
     // detached from the document.
     PresentationController* presentationController();
 
     // Common send method for both ArrayBufferView and ArrayBuffer.
     void sendInternal(const uint8_t* data, size_t, ExceptionState&);
 
+    void handleMessageQueue();
+
+    // Callbacks invoked from BlobLoader.
+    void didFinishLoadingBlob(PassRefPtr<DOMArrayBuffer>);
+    void didFailLoadingBlob(FileError::ErrorCode);
+
     String m_id;
     String m_url;
     WebPresentationSessionState m_state;
+
+    // For Blob data handling.
+    Member<BlobLoader> m_blobLoader;
+    Deque<OwnPtr<Message>> m_messages;
 };
 
 } // namespace blink
 
 #endif // PresentationSession_h