Add a NavigationThrottle to the public content/ interface

content/browser/frame_host/navigator_impl.cc

Index: content/browser/frame_host/navigator_impl.cc
diff --git a/content/browser/frame_host/navigator_impl.cc b/content/browser/frame_host/navigator_impl.cc
index b2be362dfb61d9b6904098078d4c62f5f2c1cbc6..8e2ccf271256fc0fd2f9a49e8c7d81580d08c9d3 100644
--- a/content/browser/frame_host/navigator_impl.cc
+++ b/content/browser/frame_host/navigator_impl.cc
@@ -158,8 +158,10 @@ void NavigatorImpl::DidStartProvisionalLoad(
     render_frame_host->SetNavigationHandle(scoped_ptr<NavigationHandleImpl>());
   }
 
-  render_frame_host->SetNavigationHandle(
-      NavigationHandleImpl::Create(url, is_main_frame, delegate_));
+  GURL filtered_url = url;
+  render_frame_host->GetProcess()->FilterURL(false, &filtered_url);
+  render_frame_host->SetNavigationHandle(NavigationHandleImpl::Create(
+      url, filtered_url, is_main_frame, delegate_));

[nasko, 2015/08/31 23:25:15]

Why do we need both? We never keep the two around in today's navigation logic,
do we?

[clamy, 2015/09/03 15:30:51]

We need to provide the filtered url to the throttles, and we also need to keep
the unfiltered one to do proper checks with what is sent by the renderer. In
order to filter the url, we need access to the process, which we currently can't
do from the NavigationHandle (in particular with PlzNavigate, in the current
architecture we could keep a pointer to the renderer). Hence why I'm keeping
both.

[nasko, 2015/09/04 23:36:49]

Where do we do those checks? Why can't we frontload the checks? Also, if we got
an invalid URL from a renderer, it is likely a good reason for terminating the
process.

 }
 
 void NavigatorImpl::DidFailProvisionalLoadWithError(