remoting: Add out-of-line copy ctors for complex classes.

remoting/test/fake_socket_factory.cc

Index: remoting/test/fake_socket_factory.cc
diff --git a/remoting/test/fake_socket_factory.cc b/remoting/test/fake_socket_factory.cc
index ed12013480959ffa0a1549a78da22f0b2a22abc6..1781185b1163ba870d46827a18ed6414ca75dde9 100644
--- a/remoting/test/fake_socket_factory.cc
+++ b/remoting/test/fake_socket_factory.cc
@@ -166,6 +166,9 @@ FakePacketSocketFactory::PendingPacket::PendingPacket(
     : from(from), to(to), data(data), data_size(data_size) {
 }
 
+FakePacketSocketFactory::PendingPacket::PendingPacket(
+    const PendingPacket& other) = default;
+
 FakePacketSocketFactory::PendingPacket::~PendingPacket() {
 }