Introduce SubframeNavigationFilteringThrottle

components/subresource_filter/content/browser/subframe_navigation_filtering_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_navigation_filtering_throttle.h"
+
+#include "base/bind.h"
+#include "base/logging.h"
+#include "content/public/browser/navigation_handle.h"
+
+namespace subresource_filter {
+
+SubframeNavigationFilteringThrottle::SubframeNavigationFilteringThrottle(
+    content::NavigationHandle* handle,
+    AsyncDocumentSubresourceFilter* parent_frame_filter)
+    : content::NavigationThrottle(handle),
+      parent_frame_filter_(parent_frame_filter),
+      weak_ptr_factory_(this) {
+  DCHECK(!handle->IsInMainFrame());
+  DCHECK(parent_frame_filter_);
+}
+
+SubframeNavigationFilteringThrottle::~SubframeNavigationFilteringThrottle() {}
+
+content::NavigationThrottle::ThrottleCheckResult
+SubframeNavigationFilteringThrottle::WillStartRequest() {
+  return DeferToCalculateLoadPolicy();
+}
+
+content::NavigationThrottle::ThrottleCheckResult
+SubframeNavigationFilteringThrottle::WillRedirectRequest() {
+  return DeferToCalculateLoadPolicy();
+}
+
+content::NavigationThrottle::ThrottleCheckResult
+SubframeNavigationFilteringThrottle::DeferToCalculateLoadPolicy() {
+  parent_frame_filter_->GetLoadPolicyForSubdocument(
+      navigation_handle()->GetURL(),
+      base::Bind(&SubframeNavigationFilteringThrottle::OnCalculatedLoadPolicy,
+                 weak_ptr_factory_.GetWeakPtr()));
+  return content::NavigationThrottle::ThrottleCheckResult::DEFER;
+}
+
+void SubframeNavigationFilteringThrottle::OnCalculatedLoadPolicy(
+    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 == LoadPolicy::DISALLOW) {
+    parent_frame_filter_->ReportDisallowedLoad();
+    navigation_handle()->CancelDeferredNavigation(
+        content::NavigationThrottle::CANCEL);
+  } else {
+    navigation_handle()->Resume();
+  }
+}
+
+}  // namespace subresource_filter