Fixes crash where the browser crashed when visiting WebVR pages without VR Services installed.

device/vr/vr_service_impl.cc

Index: device/vr/vr_service_impl.cc
diff --git a/device/vr/vr_service_impl.cc b/device/vr/vr_service_impl.cc
index 05b75b07221d06b45bbbbd7a4705902fad213047..1eb82d053bc0a73ee0cc9ff03da6da5134c5a987 100644
--- a/device/vr/vr_service_impl.cc
+++ b/device/vr/vr_service_impl.cc
@@ -36,8 +36,8 @@ void VRServiceImpl::SetClient(mojom::VRServiceClientPtr service_client,
   client_ = std::move(service_client);
   VRDeviceManager* device_manager = VRDeviceManager::GetInstance();
   // Once a client has been connected AddService will force any VRDisplays to
-  // send OnConnected to it so that it's populated with the currently active
-  // displays. Thereafer it will stay up to date by virtue of listening for new
+  // send ConnectDevice to it so that it's populated with the currently active
+  // displays. Thereafter it will stay up to date by virtue of listening for new
   // connected events.
   device_manager->AddService(this);
   callback.Run(device_manager->GetNumberOfConnectedDevices());
@@ -69,6 +69,10 @@ void VRServiceImpl::OnVRDisplayInfoCreated(
                    "process is not established";
     return;
   }
+  if (!display_info) {
+    // We cannot instantiate a display with a null display info.

[amp, 2017/03/24 22:33:31]

Would be nice to call out (until we fix it) the reason that we can get null
display info (because libraries don't exist etc).

[tiborg, 2017/03/27 14:53:25]

Added a comment to clarify.

+    return;
+  }
   displays_[device] = base::MakeUnique<VRDisplayImpl>(
       device, this, client_.get(), std::move(display_info));
 }