PlzNavigate: Move navigation-level mixed content checks to the browser.

content/browser/loader/resource_loader.cc

 // Copyright (c) 2012 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 "content/browser/loader/resource_loader.h"
 
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/location.h"
@@ skipping 145 matching lines @@
   if (login_delegate_.get())
     login_delegate_->OnRequestCancelled();
   ssl_client_auth_handler_.reset();
 
   // Run ResourceHandler destructor before we tear-down the rest of our state
   // as the ResourceHandler may want to inspect the URLRequest and other state.
   handler_.reset();
 }
 
 void ResourceLoader::StartRequest() {
-  if (delegate_->HandleExternalProtocol(this, request_->url())) {
-    CancelAndIgnore();
-    return;
-  }
-
   // Give the handler a chance to delay the URLRequest from being started.
   bool defer_start = false;
   if (!handler_->OnWillStart(request_->url(), &defer_start)) {
     Cancel();
     return;
   }
 
+  if (delegate_->HandleExternalProtocol(this, request_->url())) {
+    CancelAndIgnore();
+    return;
+  }
+

[carlosk, 2016/07/18 14:37:13]

This order change was necessary to allow mixed-content security checks to block
requests that would be handled externally.

[clamy, 2016/07/18 15:20:37]

This seems wrong. The mixed content_check will not be executed synchronously in
handler_->OnWillStart. So by moving the call to
delegate_->HandleExternalProtocol later, you just send a call to the Throttle on
the UI thread and then cancel the request on the IO thread before you get the
result of the mixed content check.

[carlosk, 2016/07/19 13:31:01]

Thanks for pointing that out. My latest patch should have dealt with that issue,
including for the redirect case.

   TRACE_EVENT_WITH_FLOW0("loading", "ResourceLoader::StartRequest", this,
                          TRACE_EVENT_FLAG_FLOW_OUT);
   if (defer_start) {
     deferred_stage_ = DEFERRED_START;
   } else {
     StartRequestInternal();
   }
 }
 
 void ResourceLoader::CancelRequest(bool from_renderer) {
@@ skipping 541 matching lines @@
     }
 
     UMA_HISTOGRAM_ENUMERATION("Net.Prefetch.Pattern", status, STATUS_MAX);
   } else if (request_->response_info().unused_since_prefetch) {
     TimeDelta total_time = base::TimeTicks::Now() - request_->creation_time();
     UMA_HISTOGRAM_TIMES("Net.Prefetch.TimeSpentOnPrefetchHit", total_time);
   }
 }
 
 }  // namespace content