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

content/browser/loader/resource_loader.cc

Index: content/browser/loader/resource_loader.cc
diff --git a/content/browser/loader/resource_loader.cc b/content/browser/loader/resource_loader.cc
index 273c4d8023890a30889b1cb3999a5760e8aa6d71..e05e09733e90914690a40ac1052987f88c78f5fb 100644
--- a/content/browser/loader/resource_loader.cc
+++ b/content/browser/loader/resource_loader.cc
@@ -163,11 +163,6 @@ ResourceLoader::~ResourceLoader() {
 }
 
 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)) {
@@ -175,6 +170,11 @@ void ResourceLoader::StartRequest() {
     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) {