This patch enables "mailto" links in WebViews.

extensions/browser/guest_view/web_view/web_view_guest.cc

Index: extensions/browser/guest_view/web_view/web_view_guest.cc
diff --git a/extensions/browser/guest_view/web_view/web_view_guest.cc b/extensions/browser/guest_view/web_view/web_view_guest.cc
index fbf9286f7857a457009bff97f6b2b55379f22499..589fe85d7dfcac37efc6bfda56702f5c29c51d49 100644
--- a/extensions/browser/guest_view/web_view/web_view_guest.cc
+++ b/extensions/browser/guest_view/web_view/web_view_guest.cc
@@ -814,6 +814,10 @@ void WebViewGuest::DidFailProvisionalLoad(
     int error_code,
     const base::string16& error_description,
     bool was_ignored_by_handler) {
+  // Suppress loadabort for "mailto" URLs.
+  if (validated_url.SchemeIs("mailto"))

[lazyboy, 2015/07/07 19:32:11]

This seems like a hack, can you explain what's going on?

With your change, what happens when you click on mailto: link inside webview?
This behavior mimics whatever happens when you click on mailto: in a tab?

[paulmeyer, 2015/07/08 17:20:16]

Yes, it does exactly what happens in a tab. With a webview though, you also get
a loadabort because the actual page in the webview didn't navigate. That's what
I'm suppressing here.

[lazyboy, 2015/07/10 19:46:50]

When we click mailto: from a regular tab page, does that also trigger
DidProvisionalLoad then? (And that seems odd).

[paulmeyer, 2015/07/13 19:47:14]

Yes it does, and it ends up calling
NavigatorImpl::DidFailProvisionalLoadWithError, which for a WebView then
triggers a loadabort. I don't want that to happen though so I suppress just
that. Everything else that happens already happens in a regular tab, so I think
it is normal.

+    return;
+
   LoadAbort(!render_frame_host->GetParent(), validated_url, error_code,
             net::ErrorToShortString(error_code));
 }