Change the views sign-in dialog to be tab modal.

chrome/browser/ui/signin_view_controller_delegate.h

Index: chrome/browser/ui/signin_view_controller_delegate.h
diff --git a/chrome/browser/ui/signin_view_controller_delegate.h b/chrome/browser/ui/signin_view_controller_delegate.h
index 6f9de730afaa68b05ed917bc8a88e0dbd49901a1..da0af486da38b17f6ff793042ff3b16c4575b47e 100644
--- a/chrome/browser/ui/signin_view_controller_delegate.h
+++ b/chrome/browser/ui/signin_view_controller_delegate.h
@@ -46,6 +46,7 @@ class SigninViewControllerDelegate : public content::WebContentsDelegate {
       SigninViewController* signin_view_controller,
       Browser* browser);
 
+  // Closes the modal sign-in dialog.
   void CloseModalSignin();
 
   // Either navigates back in the signin flow if the history state allows it or
@@ -65,6 +66,17 @@ class SigninViewControllerDelegate : public content::WebContentsDelegate {
   content::WebContents* web_contents_for_testing() { return web_contents_; }
 
  protected:
+  // The presentation type of the modal sign-in dialog.
+  enum DialogModalType {
+    // The sign-in dialog is presented as tab modal: the user may interact with
+    // the parent window and the dialog is dismissed on tab navigation.
+    TAB_MODAL,
+
+    // The sign-in dialog is presented as window modal: the user cannot interact
+    // with the parent window an

[Peter Kasting, 2017/01/11 01:24:45]

Nit: Comment cut off

[msarda, 2017/01/11 09:54:25]

Removed this enum.

+    WINDOW_MODAL
+  };
+
   SigninViewControllerDelegate(SigninViewController* signin_view_controller,
                                content::WebContents* web_contents);
   ~SigninViewControllerDelegate() override;