Added UMA statistics for change passwords in the Password Manager

chrome/browser/ui/views/passwords/manage_passwords_bubble_view.cc

Index: chrome/browser/ui/views/passwords/manage_passwords_bubble_view.cc
diff --git a/chrome/browser/ui/views/passwords/manage_passwords_bubble_view.cc b/chrome/browser/ui/views/passwords/manage_passwords_bubble_view.cc
index 0095032732fd4758a246bf85caef5ae57cbc68a9..2f3038114cd91c758acb7331a7883e7bf9e82e96 100644
--- a/chrome/browser/ui/views/passwords/manage_passwords_bubble_view.cc
+++ b/chrome/browser/ui/views/passwords/manage_passwords_bubble_view.cc
@@ -1027,9 +1027,6 @@ ManagePasswordsBubbleView::UpdatePendingView::UpdatePendingView(
         parent->model()->pending_password().username_value);
     item = selection_view_;
   } else {
-    DCHECK_EQ(1u, parent->model()->local_credentials().size());

[dvadym, 2015/08/19 11:47:56]

Since https://codereview.chromium.org/1297963002/ it's legitimate case when he
have more than 1 local_credentials and 1 account bubble because in case when we
show overridden bubble it's always 1 account bubble. So these checks are not
true anymore

[vasilii, 2015/08/20 15:11:48]

You are talking about password_overriden case?
It seems like a bad bug that we end up in this bubble then.
PasswordManager::OnLoginSuccessful contains a condition that password_overriden
means "Update". But the password store can be empty.

[dvadym, 2015/08/21 14:09:53]

In case of password_overridden, password store can't be empty, since the user
overrode previously stored password. See description of CL for more details.

-    DCHECK_EQ(parent->model()->local_credentials()[0]->username_value,
-              parent->model()->pending_password().username_value);

[vasilii, 2015/08/19 13:01:18]

If this is untrue then there is a bug in the line # 1091.

Ideally you should summarize everything in a comment here.

[dvadym, 2015/08/20 11:10:11]

Thanks, there was a bug in the line 1091. Fixed.

I've added comment
// |pending_password()| is a form that should be updated, so it should be used
when the user clicks "Update".
I think that the main point which can cause errors here, it's that
pending_password() should be used for Updating (i.e.error in the line #1091), so
I've added this to comment.

[vasilii, 2015/08/20 15:11:48]

I'm concerned about this change. It violates the comment to 
PasswordFormManager::Update. I totally admit that PasswordStore::UpdateLogin may
fail silently.

[dvadym, 2015/08/21 14:09:53]

Strictly speaking using |pending_password| for argument of call of PasswordStore
doesn't violates UpdateLogin, because |pending_password| is one of
|best_matches| in this case
(https://code.google.com/p/chromium/codesearch#chromium/src/components/passwor...).

I agree that this is not obvious. So I'm going to change comment for UpdateLogin
to the following:
...|credentials_to_update| should be one of |best_matches_| or
|pending_credentials|.

I've added comments to PasswordManagerClient::PromptUserToSaveOrUpdatePassword

     std::vector<const autofill::PasswordForm*> forms;
     forms.push_back(&parent->model()->pending_password());
     item = new ManagePasswordItemsView(parent_->model(), forms);
@@ -1094,6 +1091,8 @@ void ManagePasswordsBubbleView::UpdatePendingView::ButtonPressed(
       parent_->model()->OnUpdateClicked(
           *parent_->model()->local_credentials()[0]);
     }
+  } else {
+    parent_->model()->OnNopeUpdateClicked();
   }
   parent_->Close();
 }