bluetooth: Standardize Bluetooth adapter access in Adapter service.

device/bluetooth/adapter_factory.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 <utility>
+
+#include "base/memory/ptr_util.h"
+#include "device/bluetooth/adapter.h"
+#include "device/bluetooth/adapter_factory.h"
+#include "device/bluetooth/bluetooth_adapter_factory.h"
+#include "mojo/public/cpp/bindings/strong_binding.h"
+
+namespace bluetooth {
+
+AdapterFactory::AdapterFactory() : weak_ptr_factory_(this) {}
+AdapterFactory::~AdapterFactory() {}
+
+// static
+void AdapterFactory::Create(mojom::AdapterFactoryRequest request) {
+  mojo::MakeStrongBinding(base::MakeUnique<AdapterFactory>(),
+                          std::move(request));
+}
+
+void AdapterFactory::GetAdapter(mojom::AdapterRequest request,
+                                mojom::AdapterClientPtr client,
+                                const GetAdapterCallback& callback) {
+  if (device::BluetoothAdapterFactory::IsBluetoothAdapterAvailable()) {
+    device::BluetoothAdapterFactory::GetAdapter(base::Bind(
+        &AdapterFactory::OnGetAdapter, weak_ptr_factory_.GetWeakPtr(),
+        base::Passed(&request), base::Passed(&client), callback));
+  } else {
+    callback.Run(false);

[ortuno, 2016/10/05 02:07:51]

nit: You should always add comments to booleans and ints when their meaning
isn't obvious[1]:

  callback.Run(false /* is_bluetooth_supported */);

[1] See Function Argument Comments for some guidance:
https://google.github.io/styleguide/cppguide.html#Implementation_Comments

[mbrunson, 2016/10/05 17:59:04]

Done.

+  }
+}
+
+void AdapterFactory::OnGetAdapter(
+    mojom::AdapterRequest request,
+    mojom::AdapterClientPtr client,
+    const GetAdapterCallback& callback,
+    scoped_refptr<device::BluetoothAdapter> adapter) {
+  if (adapter) {

[ortuno, 2016/10/05 02:07:51]

I think we are always guaranteed to get an adapter back. Did you find any cases
where we wouldn't? You could also make it a DCHECK() to signal that the
following code assumes you always get an adapter.

[mbrunson, 2016/10/05 17:59:04]

It seems to be always guaranteed.

+    Adapter::Create(std::move(request), std::move(client), adapter);

[ortuno, 2016/10/05 02:07:51]

We were forced to make a Create method because of how AddInterface works, but I
don't think we need it anymore. Just move its implementation here.

[mbrunson, 2016/10/05 17:59:04]

Done.

+    callback.Run(true);
+  } else {
+    callback.Run(false);
+  }
+}
+
+}  // namespace bluetooth