[CrOS Tether] Create TetherConnector, which attempts to connect to a nearby tether host.

chromeos/components/tether/connect_tethering_operation.cc

Index: chromeos/components/tether/connect_tethering_operation.cc
diff --git a/chromeos/components/tether/connect_tethering_operation.cc b/chromeos/components/tether/connect_tethering_operation.cc
index b7723b7130872c4aaf97c130e509f9f26371fe6c..f63f105bce9c7b7b327e67ed388d3019bd61bec3 100644
--- a/chromeos/components/tether/connect_tethering_operation.cc
+++ b/chromeos/components/tether/connect_tethering_operation.cc
@@ -52,8 +52,11 @@ ConnectTetheringOperation::ConnectTetheringOperation(
     : MessageTransferOperation(
           std::vector<cryptauth::RemoteDevice>{device_to_connect},
           connection_manager),
+      remote_device_(device_to_connect),
       host_scan_device_prioritizer_(host_scan_device_prioritizer),
-      has_authenticated_(false) {}
+      error_code_to_return_(
+          ConnectTetheringResponse_ResponseCode::
+              ConnectTetheringResponse_ResponseCode_UNKNOWN_ERROR) {}
 
 ConnectTetheringOperation::~ConnectTetheringOperation() {}
 
@@ -68,8 +71,6 @@ void ConnectTetheringOperation::RemoveObserver(Observer* observer) {
 void ConnectTetheringOperation::OnDeviceAuthenticated(
     const cryptauth::RemoteDevice& remote_device) {
   DCHECK(remote_devices().size() == 1u && remote_devices()[0] == remote_device);
-  has_authenticated_ = true;
-
   SendMessageToDevice(remote_device, base::MakeUnique<MessageWrapper>(
                                          ConnectTetheringRequest()));
 }
@@ -83,6 +84,11 @@ void ConnectTetheringOperation::OnMessageReceived(
     return;
   }
 
+  if (!(remote_device == remote_device_)) {
+    // If the message came from another device, ignore it.
+    return;
+  }
+
   ConnectTetheringResponse* response =
       static_cast<ConnectTetheringResponse*>(message_wrapper->GetProto().get());
   if (response->response_code() ==
@@ -98,22 +104,19 @@ void ConnectTetheringOperation::OnMessageReceived(
       host_scan_device_prioritizer_->RecordSuccessfulConnectTetheringResponse(
           remote_device);
 
-      NotifyObserversOfSuccessfulResponse(response->ssid(),
-                                          response->password());
+      ssid_to_return_ = response->ssid();
+      password_to_return_ = response->password();
     } else {
       PA_LOG(ERROR) << "Received ConnectTetheringResponse from device with ID "
                     << remote_device.GetTruncatedDeviceIdForLogs() << " and "
                     << "response_code == SUCCESS, but the response did not "
                     << "contain a Wi-Fi SSID and/or password.";
-      NotifyObserversOfConnectionFailure(
-          ConnectTetheringResponse_ResponseCode::
-              ConnectTetheringResponse_ResponseCode_UNKNOWN_ERROR);
     }
   } else {
     PA_LOG(INFO) << "Received ConnectTetheringResponse from device with ID "
                  << remote_device.GetTruncatedDeviceIdForLogs() << " and "
                  << "response_code == " << response->response_code() << ".";
-    NotifyObserversOfConnectionFailure(response->response_code());
+    error_code_to_return_ = response->response_code();
   }
 
   // Now that a response has been received, the device can be unregistered.
@@ -121,13 +124,18 @@ void ConnectTetheringOperation::OnMessageReceived(
 }
 
 void ConnectTetheringOperation::OnOperationFinished() {
-  if (!has_authenticated_) {
-    // If the operation finished but the device never authenticated, there was
-    // some sort of problem connecting to the device. In this case, notify
-    // observers of a failure.
-    NotifyObserversOfConnectionFailure(
-        ConnectTetheringResponse_ResponseCode::
-            ConnectTetheringResponse_ResponseCode_UNKNOWN_ERROR);
+  // Notify observers of the results of this operation in OnOperationFinished()
+  // instead of in OnMessageReceived() because observers may delete this
+  // ConnectTetheringOperation instance. If this happens, the UnregisterDevice()
+  // call in OnMessageReceived() will cause a crash.
+
+  if (!ssid_to_return_.empty()) {
+    NotifyObserversOfSuccessfulResponse(ssid_to_return_, password_to_return_);
+  } else {
+    // At this point, either the operation finished with a failed response or
+    // no connection succeeded at all. In these cases, notify observers of a
+    // failure.
+    NotifyObserversOfConnectionFailure(error_code_to_return_);
   }
 }
 
@@ -139,14 +147,15 @@ void ConnectTetheringOperation::NotifyObserversOfSuccessfulResponse(
     const std::string& ssid,
     const std::string& password) {
   for (auto& observer : observer_list_) {
-    observer.OnSuccessfulConnectTetheringResponse(ssid, password);
+    observer.OnSuccessfulConnectTetheringResponse(remote_device_, ssid,
+                                                  password);
   }
 }
 
 void ConnectTetheringOperation::NotifyObserversOfConnectionFailure(
     ConnectTetheringResponse_ResponseCode error_code) {
   for (auto& observer : observer_list_) {
-    observer.OnConnectTetheringFailure(error_code);
+    observer.OnConnectTetheringFailure(remote_device_, error_code);
   }
 }