chromeos: Don't compile Linux shell-integration code.

This avoids a bunch of log spam at startup about failed XDG
commands. It also makes the default-browser prompt code not
get compiled for Chrome OS.

BUG=287894

Review URL: https://chromiumcodereview.appspot.com/23572036

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@222946 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index 990249f..76ae923 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -259,8 +259,10 @@
 #if !defined(OS_ANDROID)
   BackgroundModeManager::RegisterPrefs(registry);
   RegisterBrowserPrefs(registry);
+#if !defined(OS_CHROMEOS)
   RegisterDefaultBrowserPromptPrefs(registry);
-#endif
+#endif  // !defined(OS_CHROMEOS)
+#endif  // !defined(OS_ANDROID)
 
 #if defined(OS_CHROMEOS)
   chromeos::AudioDevicesPrefHandlerImpl::RegisterPrefs(registry);