network_diagnostics: Make UdpProber class abstract

To facillate testing in classes that use the UdpProber, create an
abstract UdpProber. Tests can derive from this abstract UdpProber class.

BUG=b/172994051
TEST=unit_tests --gtest_filter=UdpProberWithFakeNetworkContextTest.*

Change-Id: Ibdfba9690e996e211f1db85888f66fe15f24c75e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2545047
Commit-Queue: Kartik Hegde <khegde@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#828923}

chrome/browser/chromeos/net/network_diagnostics/udp_prober.h

@@ -6,23 +6,14 @@
 #define CHROME_BROWSER_CHROMEOS_NET_NETWORK_DIAGNOSTICS_UDP_PROBER_H_
 
 #include <cstdint>
+#include <memory>
 
 #include "base/callback.h"
 #include "base/containers/span.h"
-#include "base/memory/weak_ptr.h"
-#include "base/optional.h"
 #include "base/time/time.h"
-#include "base/timer/timer.h"
-#include "chrome/browser/chromeos/net/network_diagnostics/host_resolver.h"
-#include "mojo/public/cpp/bindings/receiver.h"
-#include "mojo/public/cpp/bindings/remote.h"
-#include "net/base/address_list.h"
-#include "net/base/ip_endpoint.h"
-#include "net/dns/public/resolve_error_info.h"
+#include "net/base/host_port_pair.h"
 #include "net/traffic_annotation/network_traffic_annotation.h"
 #include "services/network/public/mojom/network_context.mojom.h"
-#include "services/network/public/mojom/udp_socket.mojom.h"
-#include "url/gurl.h"
 
 namespace chromeos {
 namespace network_diagnostics {
@@ -31,7 +22,7 @@ namespace network_diagnostics {
 // the prober listens for received data. It confirms that data was received but
 // does not validate the content, hence no data is parsed. Used by network
 // diagnostic routines.
-class UdpProber : public network::mojom::UDPSocketListener {
+class UdpProber {
  public:
   // Lists the ways a prober may end. The callback passed into the prober's
   // constructor is invoked while exiting.
@@ -48,86 +39,20 @@ class UdpProber : public network::mojom::UDPSocketListener {
 
   using NetworkContextGetter =
       base::RepeatingCallback<network::mojom::NetworkContext*()>;
-  using ConnectCallback = base::OnceCallback<
-      void(int result, const base::Optional<net::IPEndPoint>& local_addr_out)>;
-  using SendCallback = base::OnceCallback<void(int result)>;
   using UdpProbeCompleteCallback =
       base::OnceCallback<void(int result, ProbeExitEnum probe_exit_enum)>;
 
-  // Establishes a UDP connection and sends |data| to |host_port_pair|. The
-  // traffic sent by the prober is described by |tag|. Since there is no
-  // guarantee the host specified by |host_port_pair| will respond to a UDP
-  // request, the prober will timeout with a failure after
-  // |timeout_after_host_resolution|. As such, the prober will run no longer
-  // than the time it takes to perform host resolution +
-  // |timeout_after_host_resolution|. Note that the constructor will not invoke
-  // |callback|, which is passed into UdpProber during construction. This
-  // ensures the UdpProber instance is constructed before |callback| is invoked.
-  // The UdpProber must be created on the UI thread and will invoke |callback|
-  // on the UI thread.  |network_context_getter| will be invoked on the UI
-  // thread.
-  UdpProber(NetworkContextGetter network_context_getter,
-            net::HostPortPair host_port_pair,
-            base::span<const uint8_t> data,
-            net::NetworkTrafficAnnotationTag tag,
-            base::TimeDelta timeout_after_host_resolution,
-            UdpProbeCompleteCallback callback);
-  UdpProber(const UdpProber&) = delete;
-  UdpProber& operator=(const UdpProber&) = delete;
-  ~UdpProber() override;
-
- private:
-  // Processes the results of the DNS resolution done by |host_resolver_|.
-  void OnHostResolutionComplete(
-      HostResolver::ResolutionResult& resolution_result);
-
-  // On success, the UDP socket is connected to the destination and is ready to
-  // send data. On failure, the UdpProber exits with a failure.
-  void OnConnectComplete(int result,
-                         const base::Optional<net::IPEndPoint>& local_addr_out);
-
-  // On success, the UDP socket is ready to receive data. So long as the
-  // received data is not empty, it is considered valid. The content itself is
-  // not verified.
-  void OnSendComplete(int result);
-
-  // network::mojom::UDPSocketListener:
-  void OnReceived(int32_t result,
-                  const base::Optional<net::IPEndPoint>& src_ip,
-                  base::Optional<base::span<const uint8_t>> data) override;
-
-  // Signals the end of the probe. Manages the clean up and returns a response
-  // to the caller.
-  void OnDone(int result, ProbeExitEnum probe_exit_enum);
-
-  // Handles disconnects on the UDPSocket remote and UDPSocketListener receiver.
-  void OnDisconnect();
-
-  // Gets the active profile-specific network context.
-  NetworkContextGetter network_context_getter_;
-  // Contains the hostname and port.
-  net::HostPortPair host_port_pair_;
-  // Data to be sent to the destination.
-  base::span<const uint8_t> data_;
-  // Network annotation tag describing the socket traffic.
-  net::NetworkTrafficAnnotationTag tag_;
-  // Represents the time after host resolution.
-  base::TimeDelta timeout_after_host_resolution_;
-  // Times the prober.
-  base::OneShotTimer timer_;
-  // Host resolver used for DNS lookup.
-  std::unique_ptr<HostResolver> host_resolver_;
-  // Stores the callback invoked once probe is complete or interrupted.
-  UdpProbeCompleteCallback callback_;
-  // Holds the UDPSocket remote.
-  mojo::Remote<network::mojom::UDPSocket> udp_socket_remote_;
-  // Listens to the response from hostname specified by |url_|.
-  mojo::Receiver<network::mojom::UDPSocketListener>
-      udp_socket_listener_receiver_{this};
-
-  // Must be the last member so that any callbacks taking a weak pointer to this
-  // instance are invalidated first during object destruction.
-  base::WeakPtrFactory<UdpProber> weak_factory_{this};
+  virtual ~UdpProber() = default;
+
+  // Creates a UdpProber instance which resolves |host_port_pair| and starts the
+  // UDP probe.  See implementation for more details.
+  static std::unique_ptr<UdpProber> Start(
+      NetworkContextGetter network_context_getter,
+      net::HostPortPair host_port_pair,
+      base::span<const uint8_t> data,
+      net::NetworkTrafficAnnotationTag tag,
+      base::TimeDelta timeout_after_host_resolution,
+      UdpProbeCompleteCallback callback);
 };
 
 }  // namespace network_diagnostics

chrome/browser/chromeos/net/network_diagnostics/udp_prober_unittest.cc

@@ -89,7 +89,7 @@ class UdpProberWithFakeNetworkContextTest : public ::testing::Test {
   void CreateAndExecuteUdpProber(base::span<const uint8_t> data,
                                  UdpProber::UdpProbeCompleteCallback callback) {
     ASSERT_TRUE(fake_network_context_);
-    udp_prober_ = std::make_unique<UdpProber>(
+    udp_prober_ = UdpProber::Start(
         base::BindRepeating(
             [](network::mojom::NetworkContext* network_context) {
               return network_context;