Reimplement inline signin with iframe

chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc

Index: chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc
diff --git a/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc b/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc
index f439c429aa75dd3795c9a00dc05882d51edfe1e7..71b1e444ee86ce5e55e4c502649774e94bb00a8f 100644
--- a/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc
+++ b/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc
@@ -38,6 +38,7 @@
 #include "chrome/common/extensions/extension_constants.h"
 #include "chrome/common/extensions/mime_types_handler.h"
 #include "chrome/common/render_messages.h"
+#include "chrome/common/url_constants.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/render_process_host.h"
@@ -634,6 +635,14 @@ void ChromeResourceDispatcherHostDelegate::OnResponseStarted(
     }
   }
 
+  // Ignores x-frame-options for the chrome signin UI.
+  if (request->first_party_for_cookies().GetOrigin().spec() ==
+      chrome::kChromeUIChromeSigninURL) {
+    net::HttpResponseHeaders* response_headers = request->response_headers();
+    if (response_headers->HasHeader("x-frame-options"))
+      response_headers->RemoveHeader("x-frame-options");
+  }
+
   prerender::URLRequestResponseStarted(request);
 }