Implement signin using webview

chrome/browser/guest_view/web_view/chrome_web_view_guest_delegate.cc

Index: chrome/browser/guest_view/web_view/chrome_web_view_guest_delegate.cc
diff --git a/chrome/browser/guest_view/web_view/chrome_web_view_guest_delegate.cc b/chrome/browser/guest_view/web_view/chrome_web_view_guest_delegate.cc
index 2a9680964558c9cae040026b761e66c3bd32861c..b44de2a097923afdd1274363f00c70cc9af0ed92 100644
--- a/chrome/browser/guest_view/web_view/chrome_web_view_guest_delegate.cc
+++ b/chrome/browser/guest_view/web_view/chrome_web_view_guest_delegate.cc
@@ -142,6 +142,18 @@ void ChromeWebViewGuestDelegate::OnGuestReady() {
   zoom_controller->SetZoomMode(ZoomController::ZOOM_MODE_ISOLATED);
 }
 
+void ChromeWebViewGuestDelegate::OnWillDetachFromEmbedder() {
+  content::WebContents* embedder_web_contents =
+      web_view_guest()->embedder_web_contents();
+  if (!embedder_web_contents)
+    return;
+
+  ZoomController* zoom_controller = ZoomController::FromWebContents(
+      web_view_guest()->embedder_web_contents());
+  if (zoom_controller)
+    zoom_controller->RemoveObserver(this);
+}
+
 void ChromeWebViewGuestDelegate::OnGuestDestroyed() {
   // Clean up custom context menu items for this guest.
   extensions::MenuManager* menu_manager = extensions::MenuManager::Get(