Remove deceptive "missing kernel support" error message

There are a number of other reasons why the sandbox process launcher may
fail to launch a child. Not sure why the original authors jumped to this
conclusion. There have been a couple of instances where folks headed down
the wrong path trying to diagnose an issue after seeing this error.

Change-Id: I558523bfbef8ae706b1598f9de2a543189de9624
Reviewed-on: https://chromium-review.googlesource.com/782366Reviewed-by: Ken Rockot <rockot@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#518399}

services/service_manager/runner/host/service_process_launcher.cc

@@ -175,10 +175,8 @@ void ServiceProcessLauncher::DoLaunch(
   if (!IsUnsandboxedSandboxType(sandbox_type_)) {
     child_process_ =
         sandbox::NamespaceSandbox::LaunchProcess(*child_command_line, options);
-    if (!child_process_.IsValid()) {
-      LOG(ERROR) << "Starting the process with a sandbox failed. Missing kernel"
-                 << " support.";
-    }
+    if (!child_process_.IsValid())
+      LOG(ERROR) << "Starting the process with a sandbox failed.";
   } else
 #endif
   {