Add flag to show toolkit-views dialogs on Mac, start with HTTP-Auth.

chrome/browser/ui/cocoa/login_prompt_cocoa.mm

Index: chrome/browser/ui/cocoa/login_prompt_cocoa.mm
diff --git a/chrome/browser/ui/cocoa/login_prompt_cocoa.mm b/chrome/browser/ui/cocoa/login_prompt_cocoa.mm
index 39d63941aba0eda1f697029f7d8dfffa6f3cd232..c2a6a8ea4cdb8dcacc5b6f8bb5574e31fa466f7a 100644
--- a/chrome/browser/ui/cocoa/login_prompt_cocoa.mm
+++ b/chrome/browser/ui/cocoa/login_prompt_cocoa.mm
@@ -11,6 +11,7 @@
 #include "base/strings/sys_string_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/tab_contents/tab_util.h"
+#include "chrome/browser/ui/browser_dialogs.h"
 #import "chrome/browser/ui/cocoa/constrained_window/constrained_window_custom_sheet.h"
 #include "chrome/browser/ui/cocoa/constrained_window/constrained_window_mac.h"
 #include "chrome/browser/ui/login/login_prompt.h"
@@ -126,6 +127,8 @@ class LoginHandlerMac : public LoginHandler,
 // static
 LoginHandler* LoginHandler::Create(net::AuthChallengeInfo* auth_info,
                                    net::URLRequest* request) {
+  if (chrome::ToolkitViewsDialogsEnabled())
+    return chrome::CreateLoginHandlerViews(auth_info, request);
   return new LoginHandlerMac(auth_info, request);
 }