Revert of [Password Manager] Convert |pending_login_managers_| to an array of scoped_refptr  (patchset #5 id:400001 of https://codereview.chromium.org/2900693002/ )

Reason for revert:
I am very sorry for reverting this CL. My reasons are described in detail in https://crbug.com/725883#c3, in summary they are:
(1) the design can be made to satisfy the requirements without refcounting
(2) there is some urgency in removing the refcounting from the codebase before people start building on it and it will become difficult to remove.

Cheers,
Vaclav

Original issue's description:
> [Password Manager] Convert |pending_login_managers_| to an array of scoped_refptr
>
> Before this CL, |pending_login_managers_| was an array of unique_ptr. So, we have to pass ownership to | PasswordsClientUIDelegate|. When manual fallback for password saving is implemented, both PasswordManager and PasswordsClientUIDelegate should have access to the PasswordFormManager.
>
> Another issue that this CL fixes: the matched PasswordFormManager is removed from |pending_login_managers_| on form submission (https://cs.chromium.org/chromium/src/components/password_manager/core/browser/password_manager.cc?rcl=2f63ef02c274ccc73241c9723ffc3edb94f7529e&l=356). If the login has failed, we might still need that PasswordFormManager in |pending_login_managers_|  and have to re-create it.
>
> BUG=725883
> TEST=PasswordManagerTest.InPageNavigation
>
> Review-Url: https://codereview.chromium.org/2900693002
> Cr-Commit-Position: refs/heads/master@{#475889}
> Committed: https://chromium.googlesource.com/chromium/src/+/b31c9aa77f4ab68acbfc4b2a01216ec0f42e07c9

TBR=dvadym@chromium.org,vasilii@chromium.org,melandory@chromium.org,kolos@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=725883

Review-Url: https://codereview.chromium.org/2926833002
Cr-Commit-Position: refs/heads/master@{#477588}
40 files changed