Fix remoting_unittests that are failing on 32-bit linux

remoting/host/security_key/remote_security_key_ipc_constants.cc

Index: remoting/host/security_key/remote_security_key_ipc_constants.cc
diff --git a/remoting/host/security_key/remote_security_key_ipc_constants.cc b/remoting/host/security_key/remote_security_key_ipc_constants.cc
index 227b284f09c78df3af11180ea0a0450f32ac8b2c..b3b5234e2d58fa9dd3bb2b5aa61f1fc66900d21d 100644
--- a/remoting/host/security_key/remote_security_key_ipc_constants.cc
+++ b/remoting/host/security_key/remote_security_key_ipc_constants.cc
@@ -4,6 +4,7 @@
 
 #include "remoting/host/security_key/remote_security_key_ipc_constants.h"
 
+#include "base/environment.h"
 #include "base/lazy_instance.h"
 
 namespace {
@@ -34,4 +35,15 @@ void SetRemoteSecurityKeyIpcChannelNameForTest(
   g_remote_security_key_ipc_channel_name.Get() = channel_name;
 }
 
+std::string GetChannelNamePathPrefixForTest() {
+  std::string path_prefix;
+#if defined(OS_LINUX)
+  path_prefix = "/dev/socket/";
+  std::unique_ptr<base::Environment> env(base::Environment::Create());
+  if (env->GetVar(base::env_vars::kHome, &path_prefix))
+    path_prefix += "/";
+#endif
+  return path_prefix;
+}
+
 }  // namespace remoting