QUIC Connection Migration: clean up the code before disabling connection...

QUIC Connection Migration: clean up the code before disabling connection migration before handshake.

This change also changes to use session's netlog instead of separate netlog to log connection migration event if connection migration will be aborted early.

Bug: 790547
Change-Id: I7a53bc315953fd57bfad3d0d249f90b200844051
Reviewed-on: https://chromium-review.googlesource.com/1141177
Commit-Queue: Zhongyi Shi <zhongyi@chromium.org>
Reviewed-by: Ryan Hamilton <rch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#576265}

net/quic/chromium/quic_chromium_client_session.cc

@@ -1673,24 +1673,23 @@ void QuicChromiumClientSession::MigrateSessionOnWriteError(
 
   LogHandshakeStatusOnConnectionMigrationSignal();
 
-  const NetLogWithSource migration_net_log = NetLogWithSource::Make(
-      net_log_.net_log(), NetLogSourceType::QUIC_CONNECTION_MIGRATION);
-  migration_net_log.BeginEvent(
-      NetLogEventType::QUIC_CONNECTION_MIGRATION_TRIGGERED,
-      base::Bind(&NetLogQuicConnectionMigrationTriggerCallback, "WriteError"));
-
   NetworkChangeNotifier::NetworkHandle new_network =
       stream_factory_->FindAlternateNetwork(
           GetDefaultSocket()->GetBoundNetwork());
   if (new_network == NetworkChangeNotifier::kInvalidNetworkHandle) {
     // No alternate network found.
     HistogramAndLogMigrationFailure(
-        migration_net_log, MIGRATION_STATUS_NO_ALTERNATE_NETWORK,
-        connection_id(), "No alternate network found");
+        net_log_, MIGRATION_STATUS_NO_ALTERNATE_NETWORK, connection_id(),
+        "No alternate network found");
     OnNoNewNetwork();
     return;
   }
 
+  const NetLogWithSource migration_net_log = NetLogWithSource::Make(
+      net_log_.net_log(), NetLogSourceType::QUIC_CONNECTION_MIGRATION);
+  migration_net_log.BeginEvent(
+      NetLogEventType::QUIC_CONNECTION_MIGRATION_TRIGGERED,
+      base::Bind(&NetLogQuicConnectionMigrationTriggerCallback, "WriteError"));
   MigrationResult result =
       Migrate(new_network, connection()->peer_address().impl().socket_address(),
               /*close_session_on_error=*/false, migration_net_log);
@@ -2021,47 +2020,48 @@ void QuicChromiumClientSession::OnPathDegrading() {
   if (!stream_factory_)
     return;
 
-  const NetLogWithSource migration_net_log = NetLogWithSource::Make(
-      net_log_.net_log(), NetLogSourceType::QUIC_CONNECTION_MIGRATION);
-  migration_net_log.BeginEvent(
-      NetLogEventType::QUIC_CONNECTION_MIGRATION_TRIGGERED,
-      base::Bind(&NetLogQuicConnectionMigrationTriggerCallback,
-                 "PathDegrading"));
-
-  if (migrate_session_early_v2_) {
-    NetworkChangeNotifier::NetworkHandle alternate_network =
-        stream_factory_->FindAlternateNetwork(
-            GetDefaultSocket()->GetBoundNetwork());
   current_connection_migration_cause_ = ON_PATH_DEGRADING;
-    if (alternate_network != NetworkChangeNotifier::kInvalidNetworkHandle) {
+
+  if (!migrate_session_early_v2_) {
+    HistogramAndLogMigrationFailure(
+        net_log_, MIGRATION_STATUS_PATH_DEGRADING_NOT_ENABLED, connection_id(),
+        "Migration on path degrading not enabled");
+    return;
+  }
+
   if (GetDefaultSocket()->GetBoundNetwork() == default_network_ &&
       current_migrations_to_non_default_network_on_path_degrading_ >=
           max_migrations_to_non_default_network_on_path_degrading_) {
     HistogramAndLogMigrationFailure(
-            migration_net_log, MIGRATION_STATUS_ON_PATH_DEGRADING_DISABLED,
-            connection_id(),
+        net_log_, MIGRATION_STATUS_ON_PATH_DEGRADING_DISABLED, connection_id(),
         "Exceeds maximum number of migrations on path degrading");
-      } else {
+    return;
+  }
+
+  NetworkChangeNotifier::NetworkHandle alternate_network =
+      stream_factory_->FindAlternateNetwork(
+          GetDefaultSocket()->GetBoundNetwork());
+  if (alternate_network == NetworkChangeNotifier::kInvalidNetworkHandle) {
+    HistogramAndLogMigrationFailure(
+        net_log_, MIGRATION_STATUS_NO_ALTERNATE_NETWORK, connection_id(),
+        "No alternative network on path degrading");
+    return;
+  }
+
   LogHandshakeStatusOnConnectionMigrationSignal();
 
+  const NetLogWithSource migration_net_log = NetLogWithSource::Make(
+      net_log_.net_log(), NetLogSourceType::QUIC_CONNECTION_MIGRATION);
+  migration_net_log.BeginEvent(
+      NetLogEventType::QUIC_CONNECTION_MIGRATION_TRIGGERED,
+      base::Bind(&NetLogQuicConnectionMigrationTriggerCallback,
+                 "PathDegrading"));
   // Probe alternative network, session will migrate to the probed
   // network and decide whether it wants to migrate back to the default
   // network on success.
-        StartProbeNetwork(
-            alternate_network,
+  StartProbeNetwork(alternate_network,
                     connection()->peer_address().impl().socket_address(),
                     migration_net_log);
-      }
-    } else {
-      HistogramAndLogMigrationFailure(
-          migration_net_log, MIGRATION_STATUS_NO_ALTERNATE_NETWORK,
-          connection_id(), "No alternative network on path degrading");
-    }
-  } else {
-    HistogramAndLogMigrationFailure(
-        migration_net_log, MIGRATION_STATUS_PATH_DEGRADING_NOT_ENABLED,
-        connection_id(), "Migration on path degrading not enabled");
-  }
   migration_net_log.EndEvent(
       NetLogEventType::QUIC_CONNECTION_MIGRATION_TRIGGERED);
 }