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);

[msw, 2015/08/07 02:23:33]

It'd be simpler if this could just "return new LoginHandlerViews(auth_info,
request);", but I'm guessing we don't allow direct dependencies on c/b/ui/views
within c/b/ui/cocoa, right?

[tapted, 2015/08/07 03:40:17]

Yeah exactly. - c/b/ui/cocoa inherits the views DEPS exclusion from c/b/ui/ and
I think it's nice to keep that to encourage good separation. (there's also the
problem that LoginHandlerViews is declared in the .cc file, so it would be more
disruptive to move out). (also the fallback file -- although it's in ui/views so
not affected by DEPS -- is kept a bit neater since it's not including headers
for an assortment of different dialogs).

   return new LoginHandlerMac(auth_info, request);
 }