Mustash: Ignore --mash flag when comparing flags in UserSessionManager.

chrome/browser/chromeos/login/session/user_session_manager.cc

Index: chrome/browser/chromeos/login/session/user_session_manager.cc
diff --git a/chrome/browser/chromeos/login/session/user_session_manager.cc b/chrome/browser/chromeos/login/session/user_session_manager.cc
index 61c3de9feb182e269cc116c0439633da34662e5a..845d8b5b313468c6269788398da147810a8db16d 100644
--- a/chrome/browser/chromeos/login/session/user_session_manager.cc
+++ b/chrome/browser/chromeos/login/session/user_session_manager.cc
@@ -77,6 +77,7 @@
 #include "chrome/browser/ui/app_list/app_list_service.h"
 #include "chrome/browser/ui/ash/ash_util.h"
 #include "chrome/browser/ui/startup/startup_browser_creator.h"
+#include "chrome/common/channel_info.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/logging_chrome.h"
 #include "chrome/common/pref_names.h"
@@ -107,6 +108,7 @@
 #include "components/user_manager/user_manager.h"
 #include "components/user_manager/user_names.h"
 #include "components/user_manager/user_type.h"
+#include "components/version_info/version_info.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/storage_partition.h"
@@ -284,12 +286,32 @@ bool NeedRestartToApplyPerSessionFlags(
   if (user_manager::UserManager::Get()->IsLoggedInAsSupervisedUser())
     return false;
 
+  // When running Mus+ash, the flags stored in Profile Prefs will contain
+  // --mash, while the browser command line will not (and should not) have
+  // it, so ignore it for the purpose of comparison.
+  // TODO(mfomitchev): Find a better way. crbug.com/690083
+  bool in_mash = user_flags.HasSwitch(::switches::kMash);
+  base::CommandLine user_flags_no_mash = user_flags;
+  if (in_mash) {
+    user_flags_no_mash = base::CommandLine(user_flags.GetProgram());
+    base::CommandLine::SwitchMap switches = user_flags.GetSwitches();
+    switches.erase(::switches::kMash);
+    user_flags_no_mash = base::CommandLine(user_flags.GetProgram());
+    for (const auto& sw : switches)
+      user_flags_no_mash.AppendSwitchNative(sw.first, sw.second);
+  }
+
   if (about_flags::AreSwitchesIdenticalToCurrentCommandLine(
-          user_flags, *base::CommandLine::ForCurrentProcess(),
+          user_flags_no_mash, *base::CommandLine::ForCurrentProcess(),
           out_command_line_difference)) {
     return false;
   }
 
+  // TODO(jamescook, mfomitchev): Browser restart doesn't currently work in
+  // Mus+ash. So if we are running Mustash and we need to restart - just crash
+  // right here. crbug.com/690140
+  CHECK(!in_mash);
+
   return true;
 }