Introduce SubframeNavigationFilteringThrottle

components/subresource_filter/content/browser/subframe_filtering_navigation_throttle.cc

+// Copyright 2017 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 "components/subresource_filter/content/browser/subframe_filtering_navigation_throttle.h"
+
+#include "base/bind.h"
+#include "components/subresource_filter/content/browser/async_document_subresource_filter.h"
+#include "content/public/browser/navigation_handle.h"
+
+namespace subresource_filter {
+
+SubframeFilteringNavigationThrottle::SubframeFilteringNavigationThrottle(
+    content::NavigationHandle* handle,
+    AsyncDocumentSubresourceFilter* parent_filter)
+    : content::NavigationThrottle(handle),
+      parent_filter_(parent_filter),
+      weak_ptr_factory_(this) {
+  DCHECK(!handle->IsInMainFrame());

[engedy, 2017/02/14 22:04:33]

nit: #include "base/logging.h"

[Charlie Harrison, 2017/02/14 23:06:55]

Done.

+  DCHECK(parent_filter_);
+}
+
+SubframeFilteringNavigationThrottle::~SubframeFilteringNavigationThrottle() {}
+
+content::NavigationThrottle::ThrottleCheckResult
+SubframeFilteringNavigationThrottle::WillStartRequest() {
+  return DeferToCalculateLoadPolicy();
+}
+
+content::NavigationThrottle::ThrottleCheckResult
+SubframeFilteringNavigationThrottle::WillRedirectRequest() {
+  return DeferToCalculateLoadPolicy();
+}
+
+content::NavigationThrottle::ThrottleCheckResult
+SubframeFilteringNavigationThrottle::DeferToCalculateLoadPolicy() {
+  parent_filter_->GetLoadPolicyForSubdocument(
+      navigation_handle()->GetURL(),
+      base::Bind(&SubframeFilteringNavigationThrottle::OnCalculatedLoadPolicy,
+                 weak_ptr_factory_.GetWeakPtr()));
+  return content::NavigationThrottle::ThrottleCheckResult::DEFER;
+}
+
+void SubframeFilteringNavigationThrottle::OnCalculatedLoadPolicy(
+    blink::WebDocumentSubresourceFilter::LoadPolicy policy) {
+  // TODO(csharrison): Support WouldDisallow pattern and expose the policy for
+  // metrics. Also, cancel with BLOCK_AND_COLLAPSE when it is implemented.
+  if (policy == blink::WebDocumentSubresourceFilter::Disallow) {
+    navigation_handle()->CancelDeferredNavigation(

[engedy, 2017/02/14 22:04:32]

Should we swap this with the next line?  A comment above
CancelDeferredNavigation warns that it might lead to deleting the
NavigationHandle, and the destruction of all NavigationThrottles.

[Charlie Harrison, 2017/02/14 23:06:55]

Good catch. This would get caught in a browser test, but not these unit tests.
I'll make sure to catch this case in a browser test suite in a follow up
(possibly, when we wire these all together).

+        content::NavigationThrottle::CANCEL);
+    parent_filter_->ReportDisallowedLoad();
+  } else {
+    navigation_handle()->Resume();
+  }
+}
+
+}  // namespace subresource_filter