[first-run] Fix force-first-run-ui flag.

This CL fixes an issue where the First Run Dialog didn't show up with
the switch enabled because the user was not considered new, which skips
the First Run UI.

Bug: 849551
Change-Id: Ibef80187dada0a2b99f932bf8f1256b1bf6034c2
Reviewed-on: https://chromium-review.googlesource.com/1086684Reviewed-by: Achuith Bhandarkar <achuith@chromium.org>
Commit-Queue: calamity <calamity@chromium.org>
Cr-Commit-Position: refs/heads/master@{#564767}

chrome/browser/chromeos/login/users/chrome_user_manager.cc

@@ -3,6 +3,9 @@
 // found in the LICENSE file.
 
 #include "chrome/browser/chromeos/login/users/chrome_user_manager.h"
+
+#include "base/command_line.h"
+#include "chromeos/chromeos_switches.h"
 #include "components/user_manager/user.h"
 #include "components/user_manager/user_manager.h"
 
@@ -14,6 +17,14 @@ ChromeUserManager::ChromeUserManager(
 
 ChromeUserManager::~ChromeUserManager() {}
 
+bool ChromeUserManager::IsCurrentUserNew() const {
+  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
+  if (command_line->HasSwitch(chromeos::switches::kForceFirstRunUI))
+    return true;
+
+  return UserManagerBase::IsCurrentUserNew();
+}
+
 // static
 ChromeUserManager* ChromeUserManager::Get() {
   user_manager::UserManager* user_manager = user_manager::UserManager::Get();

chrome/browser/chromeos/login/users/chrome_user_manager.h

@@ -23,6 +23,9 @@ class ChromeUserManager : public user_manager::UserManagerBase,
   explicit ChromeUserManager(scoped_refptr<base::TaskRunner> task_runner);
   ~ChromeUserManager() override;
 
+  // user_manager::UserManagerBase:
+  bool IsCurrentUserNew() const override;
+
   // Returns current ChromeUserManager or NULL if instance hasn't been
   // yet initialized.
   static ChromeUserManager* Get();