Connect to DeviceManager lazily in WebUSBClientImpl.

content/renderer/usb/web_usb_client_impl.cc

 // Copyright 2015 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/renderer/usb/web_usb_client_impl.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/move.h"
@@ skipping 48 matching lines @@
     device::usb::DevicePtr device;
     device_manager->GetDevice(results[i]->guid, mojo::GetProxy(&device));
     (*devices)[i] = new WebUSBDeviceImpl(
         device.Pass(), mojo::ConvertTo<blink::WebUSBDeviceInfo>(results[i]));
   }
   scoped_callbacks.PassCallbacks()->onSuccess(blink::adoptWebPtr(devices));
 }
 
 }  // namespace
 
-WebUSBClientImpl::WebUSBClientImpl(content::ServiceRegistry* service_registry) {
-  service_registry->ConnectToRemoteService(mojo::GetProxy(&device_manager_));
-}
+WebUSBClientImpl::WebUSBClientImpl(content::ServiceRegistry* service_registry)
+    : service_registry_(service_registry) {}
 
 WebUSBClientImpl::~WebUSBClientImpl() {}
 
 void WebUSBClientImpl::getDevices(
     blink::WebUSBClientGetDevicesCallbacks* callbacks) {
   auto scoped_callbacks = MakeScopedUSBCallbacks(callbacks);
-  device_manager_->GetDevices(
+  GetDeviceManager()->GetDevices(
       nullptr,
       base::Bind(&OnGetDevicesComplete, base::Passed(&scoped_callbacks),
                  base::Unretained(device_manager_.get())));
 }
 
 void WebUSBClientImpl::requestDevice(
     const blink::WebUSBDeviceRequestOptions& options,
     blink::WebUSBClientRequestDeviceCallbacks* callbacks) {
   callbacks->onError(blink::WebUSBError(blink::WebUSBError::Error::Service,
                                         base::UTF8ToUTF16("Not implemented.")));
   delete callbacks;
 }
 
 void WebUSBClientImpl::setObserver(Observer* observer) {
   if (!observer_) {
     // Set up two sequential calls to GetDeviceChanges to avoid latency.
-    device_manager_->GetDeviceChanges(base::Bind(
+    device::usb::DeviceManager* device_manager = GetDeviceManager();
+    device_manager->GetDeviceChanges(base::Bind(
         &WebUSBClientImpl::OnDeviceChangeNotification, base::Unretained(this)));
-    device_manager_->GetDeviceChanges(base::Bind(
+    device_manager->GetDeviceChanges(base::Bind(
         &WebUSBClientImpl::OnDeviceChangeNotification, base::Unretained(this)));
   }
 
   observer_ = observer;
 }
 
+device::usb::DeviceManager* WebUSBClientImpl::GetDeviceManager() {
+  if (!device_manager_)
+    service_registry_->ConnectToRemoteService(mojo::GetProxy(&device_manager_));
+  return device_manager_.get();
+}
+
 void WebUSBClientImpl::OnDeviceChangeNotification(
     device::usb::DeviceChangeNotificationPtr notification) {
   if (!observer_)
     return;
 
   device_manager_->GetDeviceChanges(base::Bind(
       &WebUSBClientImpl::OnDeviceChangeNotification, base::Unretained(this)));
   for (size_t i = 0; i < notification->devices_added.size(); ++i) {
     const device::usb::DeviceInfoPtr& device_info =
         notification->devices_added[i];
     device::usb::DevicePtr device;
     device_manager_->GetDevice(device_info->guid, mojo::GetProxy(&device));
     observer_->onDeviceConnected(blink::adoptWebPtr(new WebUSBDeviceImpl(
         device.Pass(), mojo::ConvertTo<blink::WebUSBDeviceInfo>(device_info))));
   }
   for (size_t i = 0; i < notification->devices_removed.size(); ++i) {
     const device::usb::DeviceInfoPtr& device_info =
         notification->devices_removed[i];
     device::usb::DevicePtr device;
     device_manager_->GetDevice(device_info->guid, mojo::GetProxy(&device));
     observer_->onDeviceDisconnected(blink::adoptWebPtr(new WebUSBDeviceImpl(
         device.Pass(), mojo::ConvertTo<blink::WebUSBDeviceInfo>(device_info))));
   }
 }
 
 }  // namespace content