content/browser/frame_host/back_forward_cache_metrics.h

// Copyright 2019 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 CONTENT_BROWSER_FRAME_HOST_BACK_FORWARD_CACHE_METRICS_H_
#define CONTENT_BROWSER_FRAME_HOST_BACK_FORWARD_CACHE_METRICS_H_

#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/optional.h"
#include "base/time/tick_clock.h"
#include "base/time/time.h"
#include "content/common/content_export.h"

namespace url {
class Origin;
}

namespace content {
class NavigationEntryImpl;
class RenderFrameHostImpl;

// Helper class for recording metrics around history navigations.
// Associated with a main frame document and shared between all
// NavigationEntries with the same document_sequence_number for the main
// document.
//
// TODO(altimin, crbug.com/933147): Remove this class after we are done
// with implementing back-forward cache.
class BackForwardCacheMetrics
    : public base::RefCounted<BackForwardCacheMetrics> {
 public:
  // Creates a potential new metrics object for the navigation.
  // Note that this object will not be used if the entry we are navigating to
  // already has the BackForwardCacheMetrics object (which happens for history
  // navigations).
  //
  // |document_sequence_number| is the sequence number of the document
  // associated with the document associated with the navigating frame and it is
  // ignored if the navigating frame is not a main one.
  static scoped_refptr<BackForwardCacheMetrics>
  CreateOrReuseBackForwardCacheMetrics(
      NavigationEntryImpl* currently_committed_entry,
      bool is_main_frame_navigation,
      int64_t document_sequence_number);

  // Notifies that the main frame has started a navigation to an entry
  // associated with |this|.
  //
  // This is the point in time that a back-forward cache hit could be shown to
  // the user.
  //
  // Note that in some cases (synchronous renderer-initiated navigations
  // which create navigation entry only when committed) this call might
  // be missing, but they should not matter for bfcache.
  void MainFrameDidStartNavigationToDocument();

  // Notifies that an associated entry has committed a navigation.
  void DidCommitNavigation(int64_t navigation_id,
                           int64_t navigation_entry_id,
                           bool is_main_frame_navigation);

  // Records when another navigation commits away from the most recent entry
  // associated with |this|.  This is the point in time that the previous
  // document could enter the back-forward cache.
  void MainFrameDidNavigateAwayFromDocument();

  // Snapshots the state of the features active on the page before closing it.
  // It should be called at the same time when the document might have been
  // placed in the back-forward cache.
  void RecordFeatureUsage(RenderFrameHostImpl* main_frame);

  // Injects a clock for mocking time.
  // Should be called only from the UI thread.
  CONTENT_EXPORT static void OverrideTimeForTesting(base::TickClock* clock);

 private:
  friend class base::RefCounted<BackForwardCacheMetrics>;

  explicit BackForwardCacheMetrics(int64_t document_sequence_number);

  ~BackForwardCacheMetrics();

  // Recursively collects the feature usage information from the subtree
  // of a given frame.
  void CollectFeatureUsageFromSubtree(RenderFrameHostImpl* rfh,
                                      const url::Origin& main_frame_origin);

  // Main frame document sequence number that identifies all NavigationEntries
  // this metrics object is associated with.
  const int64_t document_sequence_number_;

  // NavigationHandle's ID for the last main frame navigation.
  // Should not be confused with NavigationEntryId.
  int64_t last_committed_main_frame_navigation_id_ = -1;

  int64_t last_committed_navigation_entry_id_ = -1;

  uint64_t main_frame_features_ = 0;
  // We record metrics for same-origin frames and cross-origin frames
  // differently as we might want to apply different policies for them,
  // especially for the things around web platform compatibility (e.g. ignore
  // unload handlers in cross-origin iframes but not in same-origin). The
  // details are still subject to metrics, however. NOTE: This is not related to
  // which process these frames are hosted in.
  uint64_t same_origin_frames_features_ = 0;
  uint64_t cross_origin_frames_features_ = 0;

  base::Optional<base::TimeTicks> started_navigation_timestamp_;
  base::Optional<base::TimeTicks> navigated_away_from_main_document_timestamp_;

  DISALLOW_COPY_AND_ASSIGN(BackForwardCacheMetrics);
};

}  // namespace content

#endif  // CONTENT_BROWSER_FRAME_HOST_BACK_FORWARD_CACHE_METRICS_H_