font_matching_metrics.h | Explore in Territory

// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef THIRD_PARTY_BLINK_RENDERER_CORE_FRAME_FONT_MATCHING_METRICS_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_FRAME_FONT_MATCHING_METRICS_H_

#include "base/task/single_thread_task_runner.h"
#include "services/metrics/public/cpp/ukm_source_id.h"
#include "third_party/blink/public/common/privacy_budget/identifiable_token.h"
#include "third_party/blink/public/common/privacy_budget/identifiable_token_builder.h"
#include "third_party/blink/renderer/core/execution_context/execution_context.h"
#include "third_party/blink/renderer/platform/fonts/font_description.h"
#include "third_party/blink/renderer/platform/fonts/font_fallback_priority.h"
#include "third_party/blink/renderer/platform/fonts/simple_font_data.h"
#include "third_party/blink/renderer/platform/timer.h"
#include "third_party/blink/renderer/platform/wtf/hash_functions.h"
#include "third_party/blink/renderer/platform/wtf/hash_set.h"
#include "third_party/blink/renderer/platform/wtf/text/atomic_string.h"

namespace blink {

// A (generic) wrapper around IdentifiableToken to enable its use as a HashMap
// key. The |token| represents the parameters by which a font was looked up.
// However, if |is_deleted_value| or |is_empty_value|, this key represents an
// object for HashMap's internal use only. In that case, |token| is left as a
// default value.
struct IdentifiableTokenKey { … };

// A helper that defines the hash function and the invalid 'empty value' that
// HashMap should use internally.
struct IdentifiableTokenKeyHashTraits
    : WTF::SimpleClassHashTraits<IdentifiableTokenKey> { … };

// Tracks and reports UKM metrics of attempted font family match attempts (both
// successful and not successful) by the current frame.
//
// Each local font lookup is also reported as is each mapping of generic font
// family name to its corresponding actual font family names. Local font lookups
// are deduped according to the family name looked up in the FontCache and the
// FontSelectionRequest parameters (i.e. weight, width and slope). Generic font
// family lookups are de-duped according to the generic name, the
// GenericFamilyType and the script. Both types of lookup events are reported
// regularly.
class FontMatchingMetrics { … };

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_CORE_FRAME_FONT_MATCHING_METRICS_H_
chromium/third_party/blink/renderer/core/frame/font_matching_metrics.h
