Blobs: Mechanism for creating Blobs in browser process, then transferring to renderer.

chrome/browser/extensions/blob_holder.cc

+// 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.
+
+#include "chrome/browser/extensions/blob_holder.h"
+
+#include "base/logging.h"
+#include "content/public/browser/blob_context.h"
+#include "extensions/common/extension_messages.h"
+
+DEFINE_WEB_CONTENTS_USER_DATA_KEY(extensions::BlobHolder);
+
+namespace extensions {
+
+BlobHolder::~BlobHolder() {
+}
+
+void BlobHolder::HoldBlobReference(scoped_ptr<content::BlobHandle> blob) {
+  held_blobs_.push_back(blob.release());
+}
+
+BlobHolder::BlobHolder(content::WebContents* web_contents)
+    : content::WebContentsObserver(web_contents) {
+}
+
+bool BlobHolder::OnMessageReceived(const IPC::Message& message) {
+  bool handled = true;
+  IPC_BEGIN_MESSAGE_MAP(BlobHolder, message)
+    IPC_MESSAGE_HANDLER(ExtensionHostMsg_BlobOwnershipTaken,
+                        OnBlobOwnershipTaken)
+    IPC_MESSAGE_UNHANDLED(handled = false)
+  IPC_END_MESSAGE_MAP()
+  return handled;
+}
+
+void BlobHolder::OnBlobOwnershipTaken(const std::string& uuid) {
+  for (ScopedVector<content::BlobHandle>::iterator it = held_blobs_.begin();
+       it != held_blobs_.end(); ++it) {
+    if ((*it)->uuid() == uuid) {
+      it = held_blobs_.erase(it);
+      return;
+    }
+  }
+  DLOG(ERROR) << "Tried to release a Blob we don't have ownership to. UUID: "
+      << uuid;
+}
+
+}  // namespace extensions