Add a label in URLRequest NetLog to indicate the connection migration mode

it is running with.

QUIC Connection Migration: add a label in each URLRequest to indicate
connection migration mode it's running with so that URLRequest and associated
QuicSession can be differentiated in a single NetLog if multiple CronetEngines
with different experiment configurations are running at the same time.

Bug: 774622
Change-Id: I003f0ac83efbec7ac41d16a83ef5d0230d4aa7d1
Reviewed-on: https://chromium-review.googlesource.com/804296Reviewed-by: Ryan Hamilton <rch@chromium.org>
Commit-Queue: Zhongyi Shi <zhongyi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521210}

net/log/net_log_event_type_list.h

@@ -2005,7 +2005,11 @@ EVENT_TYPE(QUIC_CHROMIUM_CLIENT_STREAM_READ_RESPONSE_TRAILERS)
 // ------------------------------------------------------------------------
 // QuicConnectionMigration
 // ------------------------------------------------------------------------
-
+// Records the QUIC connection migration mode.
+//  {
+//     "connection_migration_mode": <The connection migration mode>
+//  }
+EVENT_TYPE(QUIC_CONNECTION_MIGRATION_MODE)
 // Records that QUIC connection migration has been triggered.
 //  {
 //     "trigger": <The reason for the migration attempt>

net/quic/chromium/quic_chromium_client_session.cc

@@ -891,6 +891,25 @@ void QuicChromiumClientSession::RemoveHandle(Handle* handle) {
   handles_.erase(handle);
 }
 
+// TODO(zhongyi): replace migration_session_* booleans with
+// ConnectionMigrationMode.
+ConnectionMigrationMode QuicChromiumClientSession::connection_migration_mode()
+    const {
+  if (migrate_session_early_v2_)
+    return ConnectionMigrationMode::FULL_MIGRATION_V2;
+
+  if (migrate_session_on_network_change_v2_)
+    return ConnectionMigrationMode::NO_MIGRATION_ON_PATH_DEGRADING_V2;
+
+  if (migrate_session_early_)
+    return ConnectionMigrationMode::FULL_MIGRATION_V1;
+
+  if (migrate_session_on_network_change_)
+    return ConnectionMigrationMode::NO_MIGRATION_ON_PATH_DEGRADING_V1;
+
+  return ConnectionMigrationMode::NO_MIGRATION;
+}
+
 int QuicChromiumClientSession::WaitForHandshakeConfirmation(
     const CompletionCallback& callback) {
   if (!connection()->connected())

net/quic/chromium/quic_chromium_client_session.h

@@ -69,6 +69,15 @@ enum class MigrationResult {
   FAILURE          // Migration failed for other reasons.
 };
 
+// Mode of connection migration.
+enum class ConnectionMigrationMode {
+  NO_MIGRATION,
+  NO_MIGRATION_ON_PATH_DEGRADING_V1,
+  FULL_MIGRATION_V1,
+  NO_MIGRATION_ON_PATH_DEGRADING_V2,
+  FULL_MIGRATION_V2
+};
+
 // Result of a connectivity probing attempt.
 enum class ProbingResult {
   PENDING,                          // Probing started, pending result.
@@ -172,6 +181,11 @@ class NET_EXPORT_PRIVATE QuicChromiumClientSession
     // Returns the session's net log.
     const NetLogWithSource& net_log() const { return net_log_; }
 
+    // Returns the session's connection migration mode.
+    ConnectionMigrationMode connection_migration_mode() const {
+      return session_->connection_migration_mode();
+    }
+
     // QuicClientPushPromiseIndex::Delegate implementation
     bool CheckVary(const SpdyHeaderBlock& client_request,
                    const SpdyHeaderBlock& promise_request,
@@ -338,6 +352,9 @@ class NET_EXPORT_PRIVATE QuicChromiumClientSession
   void AddHandle(Handle* handle);
   void RemoveHandle(Handle* handle);
 
+  // Returns the session's connection migration mode.
+  ConnectionMigrationMode connection_migration_mode() const;
+
   // Waits for the handshake to be confirmed and invokes |callback| when
   // that happens. If the handshake has already been confirmed, returns OK.
   // If the connection has already been closed, returns a net error. If the

net/quic/chromium/quic_http_stream.cc

@@ -114,6 +114,11 @@ int QuicHttpStream::InitializeStream(const HttpRequestInfo* request_info,
   stream_net_log.AddEvent(
       NetLogEventType::HTTP_STREAM_REQUEST_BOUND_TO_QUIC_SESSION,
       quic_session()->net_log().source().ToEventParametersCallback());
+  stream_net_log.AddEvent(
+      NetLogEventType::QUIC_CONNECTION_MIGRATION_MODE,
+      NetLog::IntCallback(
+          "connection_migration_mode",
+          static_cast<int>(quic_session()->connection_migration_mode())));
 
   stream_net_log_ = stream_net_log;
   request_info_ = request_info;