Fixed a crash in Chrome caused by duplicate certificates

chrome/browser/ui/views/certificate_selector.cc

Index: chrome/browser/ui/views/certificate_selector.cc
diff --git a/chrome/browser/ui/views/certificate_selector.cc b/chrome/browser/ui/views/certificate_selector.cc
index f6cb4f7443b5f3bc19a98e229ecbb41e7786803f..bd9e5d5241aa325e37eb790b5325e333f3b62705 100644
--- a/chrome/browser/ui/views/certificate_selector.cc
+++ b/chrome/browser/ui/views/certificate_selector.cc
@@ -178,6 +178,18 @@ bool CertificateSelector::CanShow(content::WebContents* web_contents) {
 void CertificateSelector::Show() {
   constrained_window::ShowWebModalDialogViews(this, web_contents_);
 
+  // TODO(isandrk): A certificate that was previously provided by *both* the

[msw, 2016/08/29 17:08:29]

What exactly is the TODO here? Will you try to fix the incorrect filtering? If
that is the actual fix we want, can we avoid this change, or just add a
DCHECK(!certificates_.empty()) here instead?

[Ivan Šandrk, 2016/08/30 14:23:22]

So this is just a quick fix for the crash, the actual bug is tracked in
crbug.com/641440 and will be fixed at a later time.

+  // platform and an extension will get incorrectly filtered out if the
+  // extension stops providing it (both instances will be filtered out), hence
+  // the certificates_ array will be empty. Displaying a dialog with an empty

[msw, 2016/08/29 17:08:29]

nit: |certificates_|

[Ivan Šandrk, 2016/08/30 14:23:22]

Done.

+  // list won't make much sense for the user, and also there are some CHECKs in
+  // the code that will fail when the list is empty and that's why an early exit
+  //  is performed here. See crbug.com/641440 for more details.

[msw, 2016/08/29 17:08:29]

nit: fix indent.

[Ivan Šandrk, 2016/08/30 14:23:23]

Done.

+  if (certificates_.empty()) {
+    GetWidget()->Close();

[msw, 2016/08/29 17:08:28]

How is this dialog triggered? If the user clicks a button to open this manually,
what happens in that case? It seems odd to just no-op if the user clicks
something and expects to see a dialog. Should it show a message instead?

[Ivan Šandrk, 2016/08/30 14:23:22]

Chrome network stack requests the dialog to be open during TLS handshake, this
is not directly triggered by user action. So this behaviour should be fine.

+    return;
+  }
+
   // Select the first row automatically.  This must be done after the dialog has
   // been created.
   table_->Select(0);