This patch enables "mailto" links in WebViews.

extensions/browser/guest_view/web_view/web_view_guest.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "extensions/browser/guest_view/web_view/web_view_guest.h"
 
 #include "base/message_loop/message_loop.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "components/browsing_data/storage_partition_http_cache_data_remover.h"
@@ skipping 796 matching lines @@
 
   find_helper_.CancelAllFindSessions();
 }
 
 void WebViewGuest::DidFailProvisionalLoad(
     content::RenderFrameHost* render_frame_host,
     const GURL& validated_url,
     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));
 }
 
 void WebViewGuest::DidStartProvisionalLoadForFrame(
     content::RenderFrameHost* render_frame_host,
     const GURL& validated_url,
     bool is_error_page,
     bool is_iframe_srcdoc) {
   scoped_ptr<base::DictionaryValue> args(new base::DictionaryValue());
@@ skipping 634 matching lines @@
     scoped_ptr<base::DictionaryValue> args(new base::DictionaryValue());
     DispatchEventToView(
         new GuestViewEvent(webview::kEventExitFullscreen, args.Pass()));
   }
   // Since we changed fullscreen state, sending a Resize message ensures that
   // renderer/ sees the change.
   web_contents()->GetRenderViewHost()->WasResized();
 }
 
 }  // namespace extensions