Fix the System Profile with extensions.

chrome/browser/ui/browser.cc

Index: chrome/browser/ui/browser.cc
diff --git a/chrome/browser/ui/browser.cc b/chrome/browser/ui/browser.cc
index 1133a6fcb21540402c588dc94b548830e7f73d6b..15737de1c96c99c5e09860a3699aa9f4413dd743 100644
--- a/chrome/browser/ui/browser.cc
+++ b/chrome/browser/ui/browser.cc
@@ -365,6 +365,12 @@ Browser::Browser(const CreateParams& params)
   CHECK(IncognitoModePrefs::CanOpenBrowser(profile_));
   CHECK(!profile_->IsGuestSession() || profile_->IsOffTheRecord())
       << "Only off the record browser may be opened in guest mode";
+  DCHECK(!profile_->IsSystemProfile())
+      << "The system profile should never have a real browser.";
+  // TODO(mlerman): After this hits stable channel, see if there are counts
+  // for this metric. If not, change the DCHECK above to a CHECK.
+  if (profile_->IsSystemProfile())
+    content::RecordAction(base::UserMetricsAction("BrowserForSystemProfile"));
 
   // TODO(jeremy): Move to initializer list once flag is removed.
   if (IsFastTabUnloadEnabled())