Fail autocheckout if there is no forms in the page.

chrome/browser/ui/autofill/tab_autofill_manager_delegate.cc

Index: chrome/browser/ui/autofill/tab_autofill_manager_delegate.cc
diff --git a/chrome/browser/ui/autofill/tab_autofill_manager_delegate.cc b/chrome/browser/ui/autofill/tab_autofill_manager_delegate.cc
index 80d6c1353d72cbc9eb23258f66b054f66d67b0bd..56a79881e0ca6e7b905634a3e26e85e9ea579d2c 100644
--- a/chrome/browser/ui/autofill/tab_autofill_manager_delegate.cc
+++ b/chrome/browser/ui/autofill/tab_autofill_manager_delegate.cc
@@ -98,7 +98,8 @@ void TabAutofillManagerDelegate::SetSyncStateChangedCallback(
 }
 
 void TabAutofillManagerDelegate::OnAutocheckoutError() {
-  dialog_controller_->OnAutocheckoutError();
+  if (dialog_controller_)

[ahutter, 2013/04/10 20:00:59]

Is this change necessary? Ideally this method won't be called if there isn't a
|dialog_controller_|.

[benquan, 2013/04/10 20:12:59]

Yes, it is called from AutocheckoutManager::OnLoadedPageMetaData().

|dialog_controller_| is a WeakPtr, we should always null-test before using
WeakPtr according to class docstring. 

[ahutter, 2013/04/10 20:29:01]

If it's called and |dialog_controller_| is NULL there's a bug in our code.  The
reason I wrote this the way I did is explicitly so it _will_ crash if
|dialog_controller_| is NULL.  I see nothing in your changes that make this
check now necessary.  If this check is necessary something got/is messed up in
the logic of OnLoadedPageMetaData.

[benquan, 2013/04/11 02:17:56]

When we navigated to a page with different domain, all dialog windows will be
closed, and thus |dialog_controller_| will be NULL. We assume checkout pages
should be within the same domain. We should re-visit this when we do have pages
from different domains. For now, I replace it with a comment.

On 2013/04/10 20:29:01, ahutter wrote:

+    dialog_controller_->OnAutocheckoutError();
 }
 
 void TabAutofillManagerDelegate::ShowAutofillSettings() {