Introduce AsyncDocumentSubresourceFilter.

components/subresource_filter/content/browser/async_document_subresource_filter.h

Index: components/subresource_filter/content/browser/async_document_subresource_filter.h
diff --git a/components/subresource_filter/content/browser/async_document_subresource_filter.h b/components/subresource_filter/content/browser/async_document_subresource_filter.h
new file mode 100644
index 0000000000000000000000000000000000000000..3d4c9dd3f33ed745269e7be226707cc94ea2b57a
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+++ b/components/subresource_filter/content/browser/async_document_subresource_filter.h
@@ -0,0 +1,148 @@
+// 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_ASYNC_DOCUMENT_SUBRESOURCE_FILTER_H_
+#define COMPONENTS_SUBRESOURCE_FILTER_CONTENT_BROWSER_ASYNC_DOCUMENT_SUBRESOURCE_FILTER_H_
+
+#include <memory>
+
+#include "base/callback.h"
+#include "base/macros.h"
+#include "base/optional.h"
+#include "base/sequenced_task_runner.h"
+#include "base/threading/thread_checker.h"
+#include "components/subresource_filter/content/browser/verified_ruleset_dealer.h"
+#include "components/subresource_filter/core/common/activation_level.h"
+#include "components/subresource_filter/core/common/activation_state.h"
+#include "components/subresource_filter/core/common/document_subresource_filter.h"
+#include "url/gurl.h"
+#include "url/origin.h"
+
+namespace subresource_filter {
+
+// An asynchronous wrapper around DocumentSubresourceFilter (DSF).
+//
+// It is accessed on the UI thread and owns a DSF living on a dedicated
+// sequenced |task_runner|. Provides asynchronous access to the DSF and destroys
+// it asynchronously.
+//
+// Initially holds an empty filter in the synchronously created Core object, and
+// initializes the filter on the |task_runner| asynchronously. This lets ADSF be
+// created synchrously and be immediately used by clients on the UI thread,
+// while the DSF is retrieved on the |task_runner| in a deferred manner.
+class AsyncDocumentSubresourceFilter {
+ public:
+  using LoadPolicyCallback = base::Callback<void(LoadPolicy)>;
+
+  class Core;
+
+  // Encapsulates the parameters needed for computing the frame-level
+  // ActivationState appropriate for the frame this ADSF is created for. These
+  // parameters are posted to ADSF::Core during its initialization.
+  struct InitializationParams {
+    InitializationParams();
+
+    // Takes parameters needed for calculating the main-frame ActivationState,
+    // that is: the main-frame |document| URL, the page-level
+    // |activation_level|, and whether or not to |measure_performance|.
+    InitializationParams(GURL document_url,
+                         ActivationLevel activation_level,
+                         bool measure_performance);
+
+    // Takes parameters needed for calculating the sub-frame ActivationState,
+    // that is: the sub-frame |document| URL, the origin of its |parent|, as
+    // well as the parent's |activation_state|.
+    InitializationParams(GURL document_url,
+                         url::Origin parent_document_origin,
+                         ActivationState parent_activation_state);
+
+    ~InitializationParams();
+
+    InitializationParams(InitializationParams&& other);
+    InitializationParams& operator=(InitializationParams&& other);
+
+    // Parameters used to compute ActivationState for the |document| before
+    // creating a DocumentSubresourceFilter.
+    GURL document_url;
+    url::Origin parent_document_origin;
+    ActivationState parent_activation_state;
+
+   private:
+    DISALLOW_COPY_AND_ASSIGN(InitializationParams);
+  };
+
+  // Creates a Core and initializes it asynchronously on a |task_runner| using
+  // the supplied initialization |params| and a VerifiedRuleset taken from the
+  // |ruleset_handle|. The core remains owned by |this| object, but lives on
+  // (and is accessed on) the |task_runner|.
+  //
+  // Once the ActivationState for the current frame is calculated, it is
+  // reported back via |activation_state_callback| on the task runner associated
+  // with the current thread. If MemoryMappedRuleset is not present or
+  // malformed, then a default ActivationState is reported (with ActivationLevel
+  // equal to DISABLED).
+  //
+  // The |first_disallowed_load_callback|, if it is non-null, is invoked on the
+  // first ReportDisallowedLoad() call.
+  AsyncDocumentSubresourceFilter(
+      VerifiedRuleset::Handle* ruleset_handle,
+      InitializationParams params,
+      base::Callback<void(ActivationState)> activation_state_callback,
+      base::OnceClosure first_disallowed_load_callback);
+
+  ~AsyncDocumentSubresourceFilter();
+
+  // Computes LoadPolicy on a |task_runner| and returns it back to the calling
+  // thread via |result_callback|. If MemoryMappedRuleset is not present or
+  // malformed, then a LoadPolicy::Allow is returned.
+  void GetLoadPolicyForSubdocument(const GURL& subdocument_url,
+                                   LoadPolicyCallback result_callback);
+
+  // Invokes |first_disallowed_load_callback|, if necessary, and posts a task to
+  // call DocumentSubresourceFilter::reportDisallowedCallback() on the
+  // |task_runner|.
+  void ReportDisallowedLoad();
+
+ private:
+  // Note: Raw pointer, |core_| already holds a reference to |task_runner_|.
+  base::SequencedTaskRunner* task_runner_;
+  std::unique_ptr<Core, base::OnTaskRunnerDeleter> core_;
+  base::OnceClosure first_disallowed_load_callback_;
+
+  base::ThreadChecker thread_checker_;
+
+  DISALLOW_COPY_AND_ASSIGN(AsyncDocumentSubresourceFilter);
+};
+
+// Holds a DocumentSubresourceFilter that is created in a deferred manner in
+// Initialize(), provided there is a valid ruleset to work with.
+class AsyncDocumentSubresourceFilter::Core {
+ public:
+  Core();
+  ~Core();
+
+  // Can return nullptr even after initialization in case MemoryMappedRuleset
+  // was not present, or was malformed during it.
+  DocumentSubresourceFilter* filter() {
+    DCHECK(thread_checker_.CalledOnValidThread());
+    return filter_ ? &filter_.value() : nullptr;
+  }
+
+ private:
+  friend class AsyncDocumentSubresourceFilter;
+
+  // Computes ActivationState from |params| and initializes a DSF using it.
+  // Returns the computed activation state.
+  ActivationState Initialize(InitializationParams params,
+                             VerifiedRuleset* verified_ruleset);
+
+  base::Optional<DocumentSubresourceFilter> filter_;
+  base::ThreadChecker thread_checker_;
+
+  DISALLOW_COPY_AND_ASSIGN(Core);
+};
+
+}  // namespace subresource_filter
+
+#endif  // COMPONENTS_SUBRESOURCE_FILTER_CONTENT_BROWSER_ASYNC_DOCUMENT_SUBRESOURCE_FILTER_H_