Revert of Allow BlobDataHandles to be copied, and have their UUIDs read, on any thread.

webkit/browser/blob/blob_data_handle.cc

 // Copyright (c) 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 "webkit/browser/blob/blob_data_handle.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/sequenced_task_runner.h"
 #include "webkit/browser/blob/blob_storage_context.h"
 #include "webkit/common/blob/blob_data.h"
 
 namespace webkit_blob {
 
-BlobDataHandle::BlobDataHandleShared::BlobDataHandleShared(
-    BlobData* blob_data,
-    BlobStorageContext* context,
-    base::SequencedTaskRunner* task_runner)
+BlobDataHandle::BlobDataHandle(BlobData* blob_data, BlobStorageContext* context,
+                               base::SequencedTaskRunner* task_runner)
     : blob_data_(blob_data),
-      context_(context->AsWeakPtr()) {
+      context_(context->AsWeakPtr()),
+      io_task_runner_(task_runner) {
+  // Ensures the uuid remains registered and the underlying data is not deleted.
+  DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
   context_->IncrementBlobRefCount(blob_data->uuid());
-}
-
-BlobData* BlobDataHandle::BlobDataHandleShared::data() const {
-  return blob_data_;
-}
-
-const std::string& BlobDataHandle::BlobDataHandleShared::uuid() const {
-  return blob_data_->uuid();
-}
-
-BlobDataHandle::BlobDataHandleShared::~BlobDataHandleShared() {
-  if (context_.get())
-    context_->DecrementBlobRefCount(blob_data_->uuid());
-}
-
-BlobDataHandle::BlobDataHandle(BlobData* blob_data,
-                               BlobStorageContext* context,
-                               base::SequencedTaskRunner* task_runner)
-    : io_task_runner_(task_runner),
-      shared_(new BlobDataHandleShared(blob_data, context, task_runner)) {
-  DCHECK(io_task_runner_);
-  DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
-}
-
-BlobDataHandle::BlobDataHandle(const BlobDataHandle& other) {
-  io_task_runner_ = other.io_task_runner_;
-  shared_ = other.shared_;
+  blob_data_->AddRef();
 }
 
 BlobDataHandle::~BlobDataHandle() {
-  BlobDataHandleShared* raw = shared_.get();
-  raw->AddRef();
-  shared_ = 0;
-  io_task_runner_->ReleaseSoon(FROM_HERE, raw);
+  if (io_task_runner_->RunsTasksOnCurrentThread()) {
+    // Note: Do not test context_ or alter the blob_data_ refcount
+    // on the wrong thread.
+    if (context_.get())
+      context_->DecrementBlobRefCount(blob_data_->uuid());
+    blob_data_->Release();
+    return;
+  }
+
+  io_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&DeleteHelper, context_, base::Unretained(blob_data_)));
 }
 
 BlobData* BlobDataHandle::data() const {
   DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
-  return shared_->data();
+  return blob_data_;
 }
 
-std::string BlobDataHandle::uuid() const {
-  return shared_->uuid();
+// static
+void BlobDataHandle::DeleteHelper(
+    base::WeakPtr<BlobStorageContext> context,
+    BlobData* blob_data) {
+  if (context.get())
+    context->DecrementBlobRefCount(blob_data->uuid());
+  blob_data->Release();
 }
 
 }  // namespace webkit_blob