While trying to enable webview sign-in by default, I found a bunch of issues

chrome/browser/ui/webui/signin/inline_login_ui.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/webui/signin/inline_login_ui.h"
 
 #include "chrome/browser/extensions/chrome_extension_web_contents_observer.h"
 #include "chrome/browser/extensions/tab_helper.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/sessions/session_tab_helper.h"
 #include "chrome/common/url_constants.h"
 #include "chrome/grit/chromium_strings.h"
 #include "components/signin/core/common/profile_management_switches.h"
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/web_ui.h"
 #include "content/public/browser/web_ui_data_source.h"
+#include "extensions/browser/guest_view/guest_view_manager.h"
 #include "grit/browser_resources.h"
 #if defined(OS_CHROMEOS)
 #include "chrome/browser/ui/webui/chromeos/login/inline_login_handler_chromeos.h"
 #else
 #include "chrome/browser/ui/webui/signin/inline_login_handler_impl.h"
 #endif
 
 namespace {
 
 content::WebUIDataSource* CreateWebUIDataSource() {
@@ skipping 20 matching lines @@
                             const std::string& parent_frame_name,
                             content::RenderFrameHost* frame) {
   content::RenderFrameHost* parent = frame->GetParent();
   if (parent && parent->GetFrameName() == parent_frame_name &&
       (parent_origin.is_empty() ||
        parent->GetLastCommittedURL().GetOrigin() == parent_origin)) {
     frame_set->insert(frame);
   }
 }
 
+bool AddToSetIfSigninWebview(std::set<content::RenderFrameHost*>* frame_set,
+                             content::WebContents* web_contents) {
+  frame_set->insert(web_contents->GetMainFrame());
+  return false;
+}
+
 } // empty namespace
 
 InlineLoginUI::InlineLoginUI(content::WebUI* web_ui)
     : WebDialogUI(web_ui),
       auth_extension_(Profile::FromWebUI(web_ui)) {
   Profile* profile = Profile::FromWebUI(web_ui);
   content::WebUIDataSource::Add(profile, CreateWebUIDataSource());
 
 #if defined(OS_CHROMEOS)
   web_ui->AddMessageHandler(new chromeos::InlineLoginHandlerChromeOS());
@@ skipping 14 matching lines @@
 }
 
 InlineLoginUI::~InlineLoginUI() {}
 
 // Gets the Gaia iframe within a WebContents.
 content::RenderFrameHost* InlineLoginUI::GetAuthIframe(
     content::WebContents* web_contents,
     const GURL& parent_origin,
     const std::string& parent_frame_name) {
   std::set<content::RenderFrameHost*> frame_set;
-  web_contents->ForEachFrame(
-      base::Bind(&AddToSetIfIsAuthIframe, &frame_set,
-                 parent_origin, parent_frame_name));
+  if (switches::IsEnableWebviewBasedSignin()) {
+    extensions::GuestViewManager* manager =
+        extensions::GuestViewManager::FromBrowserContext(
+            web_contents->GetBrowserContext());
+    manager->ForEachGuest(web_contents,
+                          base::Bind(&AddToSetIfSigninWebview, &frame_set));
+  } else {
+    web_contents->ForEachFrame(
+        base::Bind(&AddToSetIfIsAuthIframe, &frame_set,
+                   parent_origin, parent_frame_name));
+  }
   DCHECK_GE(1U, frame_set.size());
   if (!frame_set.empty())
     return *frame_set.begin();
 
   return NULL;
 }