diff --git chrome/browser/chrome_browser_main.cc chrome/browser/chrome_browser_main.cc
index c06585b15b8f..763212a575ce 100644
--- chrome/browser/chrome_browser_main.cc
+++ chrome/browser/chrome_browser_main.cc
@@ -49,6 +49,7 @@
 #include "build/branding_buildflags.h"
 #include "build/build_config.h"
 #include "cc/base/switches.h"
+#include "cef/libcef/features/runtime.h"
 #include "chrome/browser/about_flags.h"
 #include "chrome/browser/active_use_util.h"
 #include "chrome/browser/after_startup_task_utils.h"
@@ -885,8 +886,10 @@ int ChromeBrowserMainParts::PreCreateThreadsImpl() {
 #if !defined(OS_ANDROID)
   // Create the RunLoop for MainMessageLoopRun() to use, and pass a copy of
   // its QuitClosure to the BrowserProcessImpl to call when it is time to exit.
+  // CEF with the Chrome runtime will create and manage its own RunLoop.
   DCHECK(!g_run_loop);
-  g_run_loop = new base::RunLoop;
+  if (!cef::IsChromeRuntimeEnabled())
+    g_run_loop = new base::RunLoop;
 
   // These members must be initialized before returning from this function.
   // Android doesn't use StartupBrowserCreator.
@@ -1580,11 +1583,13 @@ int ChromeBrowserMainParts::PreMainMessageLoopRunImpl() {
   // This step is costly and is already measured in
   // Startup.StartupBrowserCreator_Start.
   // See the comment above for an explanation of |process_command_line|.
+  // Bypass StartupBrowserCreator with CEF where |g_run_loop| is nullptr.
   const bool started =
+      !g_run_loop ||
       !process_command_line ||
       browser_creator_->Start(parsed_command_line(), base::FilePath(), profile_,
                               last_opened_profiles);
-  if (started) {
+  if (started && g_run_loop) {
 #if defined(OS_WIN) || (defined(OS_LINUX) && !defined(OS_CHROMEOS))
     // Initialize autoupdate timer. Timer callback costs basically nothing
     // when browser is not in persistent mode, so it's OK to let it ride on
diff --git ui/gtk/select_file_dialog_impl_kde.cc ui/gtk/select_file_dialog_impl_kde.cc
index f09501d6cd8e..edfc2a4c9bb5 100644
--- ui/gtk/select_file_dialog_impl_kde.cc
+++ ui/gtk/select_file_dialog_impl_kde.cc
@@ -6,6 +6,8 @@
 #include <gtk/gtk.h>
 #include <stddef.h>
 
+#undef Success
+
 #include <memory>
 #include <set>