Introduce SubframeNavigationFilteringThrottle

components/subresource_filter/content/browser/subframe_navigation_filtering_throttle.h

Index: components/subresource_filter/content/browser/subframe_navigation_filtering_throttle.h
diff --git a/components/subresource_filter/content/browser/subframe_navigation_filtering_throttle.h b/components/subresource_filter/content/browser/subframe_navigation_filtering_throttle.h
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+// 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.
+
+#ifndef COMPONENTS_SUBRESOURCE_FILTER_CONTENT_BROWSER_SUBFRAME_NAVIGATION_FILTERING_THROTTLE_H_
+#define COMPONENTS_SUBRESOURCE_FILTER_CONTENT_BROWSER_SUBFRAME_NAVIGATION_FILTERING_THROTTLE_H_
+
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "components/subresource_filter/content/browser/async_document_subresource_filter.h"
+#include "content/public/browser/navigation_throttle.h"
+
+namespace content {
+class NavigationHandle;
+}  // namespace content
+
+namespace subresource_filter {
+
+class AsyncDocumentSubresourceFilter;
+
+// NavigationThrottle responsible for filtering subframe document loads, which
+// are considered subresource loads of their parent frame, hence are subject to
+// subresource filtering using the parent frame's
+// AsyncDocumentSubresourceFilter.
+//
+// The throttle should only be instantiated for navigations occuring in
+// subframes owned by documents which already have filtering activated, and
+// therefore an associated (Async)DocumentSubresourceFilter.
+class SubframeNavigationFilteringThrottle : public content::NavigationThrottle {
+ public:
+  SubframeNavigationFilteringThrottle(
+      content::NavigationHandle* handle,
+      AsyncDocumentSubresourceFilter* parent_frame_filter);
+  ~SubframeNavigationFilteringThrottle() override;
+
+  // content::NavigationThrottle:
+  content::NavigationThrottle::ThrottleCheckResult WillStartRequest() override;
+  content::NavigationThrottle::ThrottleCheckResult WillRedirectRequest()
+      override;
+
+ private:
+  content::NavigationThrottle::ThrottleCheckResult DeferToCalculateLoadPolicy();
+  void OnCalculatedLoadPolicy(LoadPolicy policy);
+
+  // Must outlive this class.
+  AsyncDocumentSubresourceFilter* parent_frame_filter_;
+
+  base::WeakPtrFactory<SubframeNavigationFilteringThrottle> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(SubframeNavigationFilteringThrottle);
+};
+
+}  // namespace subresource_filter
+
+#endif  // COMPONENTS_SUBRESOURCE_FILTER_CONTENT_BROWSER_SUBFRAME_NAVIGATION_FILTERING_THROTTLE_H_