Print an error when trying to launch an incognito browser and incognito is disabled.

chrome/browser/ui/browser_init.cc

Index: chrome/browser/ui/browser_init.cc
diff --git a/chrome/browser/ui/browser_init.cc b/chrome/browser/ui/browser_init.cc
index 0f672f366321829d09984617a77ee05a2e2947d5..9aaa2bbcc6d29ec67f923cc91b8da8330970d417 100644
--- a/chrome/browser/ui/browser_init.cc
+++ b/chrome/browser/ui/browser_init.cc
@@ -549,6 +549,9 @@ bool BrowserInit::LaunchBrowser(const CommandLine& command_line,
   // is forced.
   if (IncognitoIsForced(command_line, profile->GetPrefs())) {
     profile = profile->GetOffTheRecordProfile();
+  } else if (command_line.HasSwitch(switches::kIncognito)) {
+    LOG(WARNING) << "Incognito mode disabled by policy, launching a normal "
+                 << "browser session.";
   }
 
   BrowserInit::LaunchWithProfile lwp(cur_dir, command_line, this);