Introduce the ThrottleManager

components/subresource_filter/content/browser/content_subresource_filter_throttle_manager.h

+// 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_CONTENT_SUBRESOURCE_FILTER_THROTTLE_MANAGER_H_
+#define COMPONENTS_SUBRESOURCE_FILTER_CONTENT_BROWSER_CONTENT_SUBRESOURCE_FILTER_THROTTLE_MANAGER_H_
+
+#include <memory>
+#include <unordered_map>
+
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "components/subresource_filter/content/browser/verified_ruleset_dealer.h"
+#include "components/subresource_filter/core/common/activation_state.h"
+#include "content/public/browser/web_contents_observer.h"
+
+namespace content {
+class NavigationHandle;
+class NavigationThrottle;
+class RenderFrameHost;
+}  // namespace content
+
+namespace subresource_filter {
+
+class AsyncDocumentSubresourceFilter;
+class ActivationStateComputingNavigationThrottle;
+
+// Simple struct which contains useful information regarding a frame's
+// activation. This includes its DocumentSubresourceFilter, as well as its
+// ActivationState.
+struct FrameActivationInfo {
+  FrameActivationInfo();
+  ~FrameActivationInfo();
+  std::unique_ptr<AsyncDocumentSubresourceFilter> subresource_filter;
+  ActivationState activation_state;
+};
+
+class ContentSubresourceFilterThrottleManager
+    : public content::WebContentsObserver {
+ public:
+  // It is expected that the Delegate outlives |this|, and manages the lifetime
+  // of this class.
+  class Delegate : public base::SupportsWeakPtr<Delegate> {
+   public:
+    // The embedder may be interested in displaying UI to the user when the
+    // first load is disallowed for a given page load.
+    virtual void OnFirstSubresourceLoadDisallowed() {}
+
+    // Let the delegate have the last word when it comes to activation. It might
+    // have a specific whitelist.
+    virtual bool ShouldVetoActivation(
+        content::NavigationHandle* navigation_handle);
+  };
+
+  ContentSubresourceFilterThrottleManager(
+      Delegate* delegate,
+      VerifiedRulesetDealer::Handle* dealer_handle,
+      content::WebContents* web_contents);
+  ~ContentSubresourceFilterThrottleManager() override;
+
+  // Must be called during a navigation, before the corresponding throttle in
+  // |ongoing_activation_throttles_| reaches WillProcessResponse.
+  void OnPageStateActivationComputed(
+      content::NavigationHandle* activated_navigation,
+      const ActivationState& state);
+
+  // content::WebContentsObserver:
+  void RenderFrameDeleted(content::RenderFrameHost* frame_host) override;
+  void ReadyToCommitNavigation(
+      content::NavigationHandle* navigation_handle) override;
+  void DidFinishNavigation(
+      content::NavigationHandle* navigation_handle) override;
+
+  void MaybeInsertNavigationThrottles(
+      content::NavigationHandle* navigation_handle,
+      std::vector<std::unique_ptr<content::NavigationThrottle>>* throttles);
+
+ private:
+  std::unique_ptr<content::NavigationThrottle>
+  MaybeCreateSubframeNavigationFilteringThrottle(
+      content::NavigationHandle* navigation_handle);
+  std::unique_ptr<content::NavigationThrottle>
+  MaybeCreateActivationStateComputingThrottle(
+      content::NavigationHandle* navigation_handle);
+
+  FrameActivationInfo* GetFrameActivationInfoForChildNavigation(
+      content::NavigationHandle* child_frame_navigation);
+
+  VerifiedRuleset::Handle* EnsureRulesetHandle();
+
+  // Map of all RenderFrameHosts that are currently activated, and their
+  // associated ActivationState and AsyncDocumentSubresourceFilters.
+  std::unordered_map<content::RenderFrameHost*,
+                     std::unique_ptr<FrameActivationInfo>>
+      activated_frame_hosts_;
+
+  // For each ongoing navigation that requires activation state computation,
+  // keeps track of the throttle that is carrying out that computation, so that
+  // the result can be retrieved when the navigation is ready to commit.
+  std::unordered_map<content::NavigationHandle*,
+                     ActivationStateComputingNavigationThrottle*>
+      ongoing_activation_throttles_;
+
+  // Lazily instantiated in EnsureRulesetHandle when the first page level
+  // activation is triggered. Will go away when there are no more activated
+  // RenderFrameHosts (i.e. activated_frame_hosts_ is empty).
+  std::unique_ptr<VerifiedRuleset::Handle> ruleset_handle_;
+
+  // These members outlive this class.
+  VerifiedRulesetDealer::Handle* dealer_handle_;
+  Delegate* delegate_;
+
+  DISALLOW_COPY_AND_ASSIGN(ContentSubresourceFilterThrottleManager);
+};
+
+}  // namespace subresource_filter
+
+#endif  // COMPONENTS_SUBRESOURCE_FILTER_CONTENT_BROWSER_CONTENT_SUBRESOURCE_FILTER_THROTTLE_MANAGER_H_