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;
+class SubframeNavigationFilteringThrottle;
+
+// The ContentSubresourceFilterThrottleManager manages NavigationThrottles in
+// order to calculate frame activation states and subframe navigation filtering,
+// within a given WebContents. It contains a mapping of all activated
+// RenderFrameHosts, along with their associated DocumentSubresourceFilters.
+//
+// The class is designed to be used by a Delegate, which shares lifetime with
+// this class (aka the typical lifetime of a WebContentsObserver). The delegate
+// will be notified of the first disallowed subresource load for a top level
+// navgation, and has veto power for frame activation.
+class ContentSubresourceFilterThrottleManager
+    : public content::WebContentsObserver {
+ public:
+  // It is expected that the Delegate outlives |this|, and manages the lifetime
+  // of this class.
+  class 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 ShouldSuppressActivation(
+        content::NavigationHandle* navigation_handle);
+  };
+
+  ContentSubresourceFilterThrottleManager(
+      Delegate* delegate,
+      VerifiedRulesetDealer::Handle* dealer_handle,
+      content::WebContents* web_contents);
+  ~ContentSubresourceFilterThrottleManager() override;
+
+  // Sets the desired page-level |activation_state| for the currently ongoing
+  // page load, identified by its main-frame |navigation_handle|. To be called
+  // by the embedder at the latest in the WillProcessResponse stage from a
+  // NavigationThrottle that was registered before the throttles created by this
+  // manager in MaybeAppendNavigationThrottles(). If this method is not called
+  // for a main-frame navigation, the default behavior is no activation for that
+  // page load.
+  void NotifyPageActivationComputed(
+      content::NavigationHandle* navigation_handle,
+      const ActivationState& activation_state);
+
+  // This method inspects |navigation_handle| and attaches navigation throttles
+  // appropriately, based on the current state of frame activation.
+  //
+  // 1. Subframe navigation filtering throttles are appended if the parent
+  // frame is activated.
+  // 2. Activation state computing throttles are appended if either the
+  // navigation is a main frame navigation, or if the parent frame is activated.
+  //
+  // Note that there is currently no ordering constraints of the throttles.

[engedy, 2017/03/10 17:36:21]

nit: no constraints on the ordering of throttles

[Charlie Harrison, 2017/03/14 23:18:31]

Done.

+  void MaybeAppendNavigationThrottles(
+      content::NavigationHandle* navigation_handle,
+      std::vector<std::unique_ptr<content::NavigationThrottle>>* throttles);

[engedy, 2017/03/10 17:36:21]

#include <vector>

[Charlie Harrison, 2017/03/14 23:18:32]

Done.

+
+  VerifiedRuleset::Handle* ruleset_handle_for_testing() {
+    return ruleset_handle_.get();
+  }
+
+ protected:
+  // content::WebContentsObserver:
+  void RenderFrameDeleted(content::RenderFrameHost* frame_host) override;
+  void ReadyToCommitNavigation(
+      content::NavigationHandle* navigation_handle) override;
+  void DidFinishNavigation(
+      content::NavigationHandle* navigation_handle) override;
+
+ private:
+  std::unique_ptr<SubframeNavigationFilteringThrottle>
+  MaybeCreateSubframeNavigationFilteringThrottle(
+      content::NavigationHandle* navigation_handle);
+  std::unique_ptr<ActivationStateComputingNavigationThrottle>
+  MaybeCreateActivationStateComputingThrottle(
+      content::NavigationHandle* navigation_handle);
+
+  // Will return nullptr if the parent frame of this navigation is not
+  // activated and has no subresource filter.

[engedy, 2017/03/10 17:36:21]

nit: (and therefore has ... ).

[Charlie Harrison, 2017/03/14 23:18:31]

Done.

+  AsyncDocumentSubresourceFilter* GetParentFilter(
+      content::NavigationHandle* child_frame_navigation);
+
+  // Calls OnFirstSubresourceLoadDisallowed on the Delegate at most once per
+  // committed, non-same-page navigation in the main frame.
+  // TODO(csharrison): Ensure IPCs from the renderer go through this path when
+  // they disallow subresource loads.
+  void MaybeCallFirstDisallowedLoad();
+
+  VerifiedRuleset::Handle* EnsureRulesetHandle();
+  void DestroyRulesetHandleIfNoLongerUsed();
+
+  // For each RenderFrameHost where the last committed load has subresource
+  // filtering activated, owns the corresponding AsyncDocumentSubresourceFilter.
+  std::unordered_map<content::RenderFrameHost*,
+                     std::unique_ptr<AsyncDocumentSubresourceFilter>>
+      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_;
+
+  // True if the current committed main frame load in this WebContents has
+  // notified the delegate that a subresource was disallowed. The callback
+  // should only be called at most once per main frame load.
+  bool current_committed_load_has_notified_disallowed_load_ = false;
+
+  // These members outlive this class.
+  VerifiedRulesetDealer::Handle* dealer_handle_;
+  Delegate* delegate_;
+
+  base::WeakPtrFactory<ContentSubresourceFilterThrottleManager>
+      weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(ContentSubresourceFilterThrottleManager);
+};
+
+}  // namespace subresource_filter
+
+#endif  // COMPONENTS_SUBRESOURCE_FILTER_CONTENT_BROWSER_CONTENT_SUBRESOURCE_FILTER_THROTTLE_MANAGER_H_