linux_aura: Default to system titlebars under some window managers.

chrome/browser/ui/browser_view_prefs.cc

Index: chrome/browser/ui/browser_view_prefs.cc
diff --git a/chrome/browser/ui/browser_view_prefs.cc b/chrome/browser/ui/browser_view_prefs.cc
index 8f89773243e8ad97ac74c837292cce5c27cb6f1b..5e98fcfa83f55e433532c4d38ab36cca0f02f3db 100644
--- a/chrome/browser/ui/browser_view_prefs.cc
+++ b/chrome/browser/ui/browser_view_prefs.cc
@@ -8,6 +8,10 @@
 #include "chrome/common/pref_names.h"
 #include "components/user_prefs/pref_registry_syncable.h"
 
+#if defined(OS_LINUX) && !defined(OS_CHROMEOS)
+#include "ui/base/x/x11_util.h"
+#endif
+
 namespace {
 
 // How long do we wait before we consider a window hung (in ms).
@@ -29,9 +33,10 @@ void RegisterBrowserViewLocalPrefs(PrefRegistrySimple* registry) {
 
 void RegisterBrowserViewProfilePrefs(
     user_prefs::PrefRegistrySyncable* registry) {
-  // TODO(mgiuca): Decide on this default depending on the window manager. See
-  // BrowserWindowGtk::GetCustomFramePrefDefault.
-  bool custom_frame_default = true;
+  bool custom_frame_default = false;
+#if defined(OS_LINUX) && !defined(OS_CHROMEOS)
+  custom_frame_default = ui::GetCustomFramePrefDefault();
+#endif
 
   registry->RegisterBooleanPref(
       prefs::kUseCustomChromeFrame,