mojo leveldb: Get profile and leveldb connected to DOMStorageContext.

components/profile_service/leveldb_thread.cc

+// 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.
+
+#include "components/profile_service/leveldb_thread.h"
+
+#include "base/bind.h"
+#include "base/message_loop/message_loop.h"
+#include "components/leveldb/leveldb_service_impl.h"
+#include "mojo/message_pump/message_pump_mojo.h"
+
+namespace profile {
+
+LevelDBThread::LevelDBThread(
+    scoped_ptr<mojo::MessageLoopRef> message_loop_ref,
+    leveldb::LevelDBServiceRequest request)
+    : base::Thread("profile/LevelDBThread"),
+      profile_service_message_loop_ref_(std::move(message_loop_ref)),
+      initial_leveldb_request_(std::move(request)) {
+  Start();
+}
+
+LevelDBThread::~LevelDBThread() {
+  Stop();
+}
+
+void LevelDBThread::OnServiceError() {
+  if (leveldb_bindings_->empty()) {
+    // We have released the last leveldb service holding on to our reference;
+    // release our service and bindings. We need to do this on connection error
+    // so that it happens on our db thread and not our parent thread.
+    leveldb_service_.reset();

[michaeln, 2016/03/16 03:11:13]

Does this cause the threadmsg loop ref to drop to zero, what happens to the
thread at this point?

+    leveldb_bindings_.reset();
+  }
+}
+
+void LevelDBThread::BindNewRequest(leveldb::LevelDBServiceRequest request) {
+  DCHECK_NE(GetThreadId(), base::PlatformThread::CurrentId());
+  task_runner()->PostTask(
+      FROM_HERE, base::Bind(&LevelDBThread::BindNewRequestImpl, this,
+                            base::Passed(&request)));
+}
+
+void LevelDBThread::BindNewRequestImpl(leveldb::LevelDBServiceRequest request) {
+  DCHECK_EQ(GetThreadId(), base::PlatformThread::CurrentId());
+  DCHECK(leveldb_service_);

[michaeln, 2016/03/16 03:11:13]

Is this racey?

What guarantees levelddb_service and bindings are not null here? If we ever get
to zero bindings with a BindNewRequestImpl task in the queue, what happens?

+  leveldb_bindings_->AddBinding(leveldb_service_.get(), std::move(request));
+}
+
+void LevelDBThread::Init() {
+  leveldb_service_.reset(new leveldb::LevelDBServiceImpl(
+      thread_message_loop_ref_.CreateRef()));
+  leveldb_bindings_.reset(new mojo::BindingSet<leveldb::LevelDBService>);
+  leveldb_bindings_->set_connection_error_handler(
+      base::Bind(&LevelDBThread::OnServiceError, base::Unretained(this)));
+  leveldb_bindings_->AddBinding(leveldb_service_.get(),
+                                std::move(initial_leveldb_request_));
+}
+
+void LevelDBThread::CleanUp() {
+  SetThreadWasQuitProperly(true);
+  profile_service_message_loop_ref_.reset();
+}
+
+}  // namespace profile