Add a NavigationThrottle to the public content/ interface

content/browser/loader/navigation_resource_throttle.cc

+// Copyright 2015 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/navigation_resource_throttle.h"
+
+#include "base/callback.h"
+#include "content/browser/frame_host/navigation_handle_impl.h"
+#include "content/browser/frame_host/render_frame_host_impl.h"
+#include "content/public/browser/resource_context.h"
+#include "content/public/browser/resource_controller.h"
+#include "content/public/browser/resource_request_info.h"
+#include "content/public/common/referrer.h"
+#include "net/url_request/redirect_info.h"
+#include "net/url_request/url_request.h"
+#include "net/url_request/url_request_context.h"
+#include "net/url_request/url_request_job_factory.h"
+#include "ui/base/page_transition_types.h"
+
+namespace content {
+
+namespace {
+typedef base::Callback<void(NavigationThrottle::ThrottleCheckResult)>
+    UIChecksPerformedCallback;
+
+void CheckWillStartRequestOnUIThread(UIChecksPerformedCallback callback,
+                                     int render_process_id,
+                                     int render_frame_host_id,
+                                     bool is_post,
+                                     const Referrer& sanitized_referrer,
+                                     bool has_user_gesture,
+                                     ui::PageTransition transition,
+                                     bool is_external_protocol) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  NavigationThrottle::ThrottleCheckResult result = NavigationThrottle::PROCEED;
+  RenderFrameHostImpl* render_frame_host =
+      RenderFrameHostImpl::FromID(render_process_id, render_frame_host_id);
+  if (render_frame_host) {

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

This doesn't seem right. Before we have gotten the response, we don't have RFH,
do we?

[davidben, 2015/09/01 21:55:18]

This is the pre-PlzNavigate codepath I believe, so we have an RFH and everything
else.

[clamy, 2015/09/03 15:30:52]

Yes this is only used by the pre-PlzNavigate codepath (and I'm basically
copy-pasting what's being done in various ResourceThrottles).

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

Let's add a comment to clarify this then. Also a TODO to remove it once we are
in PlzNavigate-only mode.

+    NavigationHandleImpl* navigation_handle =
+        render_frame_host->navigation_handle();
+    if (navigation_handle) {
+      result = navigation_handle->WillStartRequest(is_post, sanitized_referrer,
+                                                   has_user_gesture, transition,
+                                                   is_external_protocol);
+    }
+  }
+  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
+                          base::Bind(callback, result));
+}
+
+void CheckWillRedirectRequestOnUIThread(UIChecksPerformedCallback callback,
+                                        int render_process_id,
+                                        int render_frame_host_id,
+                                        const GURL& new_url,
+                                        bool new_method_is_post,
+                                        const GURL& new_referrer_url,
+                                        bool new_is_external_protocol) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  NavigationThrottle::ThrottleCheckResult result = NavigationThrottle::PROCEED;
+  RenderFrameHostImpl* render_frame_host =
+      RenderFrameHostImpl::FromID(render_process_id, render_frame_host_id);
+  if (render_frame_host) {
+    NavigationHandleImpl* navigation_handle =
+        render_frame_host->navigation_handle();
+    if (navigation_handle) {
+      RenderProcessHost* rph = RenderProcessHost::FromID(render_process_id);
+      GURL new_validated_url = new_url;
+      rph->FilterURL(false, &new_validated_url);
+      result = navigation_handle->WillRedirectRequest(
+          new_url, new_validated_url, new_method_is_post, new_referrer_url,
+          new_is_external_protocol);
+    }
+  }
+  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
+                          base::Bind(callback, result));
+}
+}  // namespace
+
+NavigationResourceThrottle::NavigationResourceThrottle(net::URLRequest* request)
+    : request_(request), weak_ptr_factory_(this) {}

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

Each member initialization on new line, no? Or has clang-format changed its
mind?

[clamy, 2015/09/03 15:30:52]

Yes apparently clang-format likes it that way nowadays.

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

Yuck :(

+
+NavigationResourceThrottle::~NavigationResourceThrottle() {}
+
+void NavigationResourceThrottle::WillStartRequest(bool* defer) {

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

Let's add DCHECKs for which thread each function is meant to be called. It
serves to both catch issues and as self-documentation.

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

Done.

+  const ResourceRequestInfo* info = ResourceRequestInfo::ForRequest(request_);
+  if (!info)
+    return;
+

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

Is it possible to know on the IO thread whether there are any throttles
registered and skip the thread hop if not? I wonder if such an optimization is
necessary.

[clamy, 2015/09/03 15:30:52]

For the redirects yes but not for the start. In any case, on Android, the
InterceptNavigationResourceHandler was doing a thread hop on each non-prerender
main frame navigation, so I don't think we worsen the situation dramatically
here. On Windows, I think the performance hit is less of an issue.

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

I think performance is always an issue. nick@chromium.org has strong position on
thread hopping, so it will be good to ensure he is on board with this.

+  int render_process_id, render_frame_id;
+  if (!info->GetAssociatedRenderFrame(&render_process_id, &render_frame_id))
+    return;
+
+  bool is_external_protocol =
+      !info->GetContext()->GetRequestContext()->job_factory()->IsHandledURL(
+          request_->url());
+  UIChecksPerformedCallback callback =
+      base::Bind(&NavigationResourceThrottle::OnUIChecksPerformed,
+                 weak_ptr_factory_.GetWeakPtr());
+  BrowserThread::PostTask(
+      BrowserThread::UI, FROM_HERE,
+      base::Bind(&CheckWillStartRequestOnUIThread, callback, render_process_id,
+                 render_frame_id, request_->method() == "POST",

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

Do we have render_frame_id at the time of sending the network request? We are
trying to divorce the navigation resource request from the renderer, right?

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

As mentionned before, this is entirely pre-PlzNavigate, so we do have the
render_frame_id, since this is initialized following a request by the renderer.
PlzNavigate uses the NavigationURLLoader to do the IO/UI communication
(effectively removing the need for renderer ids).

+                 Referrer::SanitizeForRequest(
+                     request_->url(), Referrer(GURL(request_->referrer()),
+                                               info->GetReferrerPolicy())),
+                 info->HasUserGesture(), info->GetPageTransition(),
+                 is_external_protocol));
+  *defer = true;
+}
+
+void NavigationResourceThrottle::WillRedirectRequest(
+    const net::RedirectInfo& redirect_info,
+    bool* defer) {
+  const ResourceRequestInfo* info = ResourceRequestInfo::ForRequest(request_);
+  if (!info)
+    return;
+
+  int render_process_id, render_frame_id;
+  if (!info->GetAssociatedRenderFrame(&render_process_id, &render_frame_id))
+    return;
+
+  bool new_is_external_protocol =
+      !info->GetContext()->GetRequestContext()->job_factory()->IsHandledURL(
+          request_->url());
+  UIChecksPerformedCallback callback =
+      base::Bind(&NavigationResourceThrottle::OnUIChecksPerformed,
+                 weak_ptr_factory_.GetWeakPtr());
+  BrowserThread::PostTask(
+      BrowserThread::UI, FROM_HERE,
+      base::Bind(&CheckWillRedirectRequestOnUIThread, callback,
+                 render_process_id, render_frame_id, redirect_info.new_url,
+                 redirect_info.new_method == "POST",
+                 GURL(redirect_info.new_referrer), new_is_external_protocol));
+  *defer = true;
+}
+
+const char* NavigationResourceThrottle::GetNameForLogging() const {
+  return "NavigationResourceThrottle";
+}
+
+void NavigationResourceThrottle::OnUIChecksPerformed(
+    NavigationThrottle::ThrottleCheckResult result) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  if (result == NavigationThrottle::CANCEL_AND_IGNORE) {
+    controller()->CancelAndIgnore();
+  } else {
+    controller()->Resume();
+  }
+}
+
+}  // namespace content