[Storage] Blob items are now shared between blobs. Ready for disk swap.

content/child/webblobregistry_impl.cc

 // Copyright 2013 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.
 
 #include "content/child/webblobregistry_impl.h"
 
 #include "base/files/file_path.h"
 #include "base/guid.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/shared_memory.h"
@@ skipping 32 matching lines @@
     const blink::WebString& uuid, const blink::WebBlobData& data) {
   const std::string uuid_str(uuid.utf8());
 
   storage::DataElement data_buffer;
   data_buffer.SetToEmptyBytes();
 
   sender_->Send(new BlobHostMsg_StartBuilding(uuid_str));
   size_t i = 0;
   WebBlobData::Item data_item;
   while (data.itemAt(i++, data_item)) {
+    // NOTE: data_item.length == -1 when we want to use the whole file.  This
+    // only happens when we are creating a file object in Blink, and the file
+    // object is the only item in the 'blob'.  If we use that file blob to
+    // create another blob, it is sent here as a 'file' item and not a blob,
+    // and the correct size is populated.
+    // static_cast<uint64>(-1) == kuint64max, which is what DataElement uses
+    // to specificy "use the whole file".
     if (data_item.length == 0) {
       continue;
     }
     if (data_item.type != WebBlobData::Item::TypeData &&
         data_buffer.length() != 0) {
       FlushBlobItemBuffer(uuid_str, &data_buffer);
     }
     storage::DataElement item;
     switch (data_item.type) {
       case WebBlobData::Item::TypeData: {
@@ skipping 174 matching lines @@
   DCHECK(ChildThreadImpl::current());
   sender_->Send(new StreamHostMsg_AbortBuilding(url));
 }
 
 void WebBlobRegistryImpl::unregisterStreamURL(const WebURL& url) {
   DCHECK(ChildThreadImpl::current());
   sender_->Send(new StreamHostMsg_Remove(url));
 }
 
 }  // namespace content