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diff --git a/layout/base/LayoutTelemetryTools.h b/layout/base/LayoutTelemetryTools.h
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+++ b/layout/base/LayoutTelemetryTools.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Tools for collecting and reporting layout and style telemetry */
+
+#ifndef mozilla_LayoutTelemetryTools_h
+#define mozilla_LayoutTelemetryTools_h
+
+#include "mozilla/EnumeratedArray.h"
+#include "mozilla/EnumeratedRange.h"
+#include "mozilla/FlushType.h"
+#include "mozilla/Saturate.h"
+#include "mozilla/TimeStamp.h"
+
+#define LAYOUT_TELEMETRY_RECORD(subsystem) \
+  layout_telemetry::AutoRecord a(layout_telemetry::LayoutSubsystem::subsystem)
+
+#define LAYOUT_TELEMETRY_RECORD_BASE(subsystem)     \
+  layout_telemetry::AutoRecord a(&mLayoutTelemetry, \
+                                 layout_telemetry::LayoutSubsystem::subsystem)
+
+namespace mozilla {
+namespace layout_telemetry {
+
+enum class FlushKind : uint8_t { Style, Layout, Count };
+
+enum class LayoutSubsystem : uint8_t {
+  Restyle,
+  Reflow,
+  ReflowFlex,
+  ReflowGrid,
+  ReflowTable,
+  ReflowText,
+  Count
+};
+
+using LayoutSubsystemDurations =
+    EnumeratedArray<LayoutSubsystem, LayoutSubsystem::Count, double>;
+using LayoutFlushCount =
+    EnumeratedArray<FlushKind, FlushKind::Count, SaturateUint8>;
+
+struct Data {
+  Data();
+
+  void IncReqsPerFlush(FlushType aFlushType);
+  void IncFlushesPerTick(FlushType aFlushType);
+
+  void PingTelemetry();
+
+  // Send the current number of flush requests for aFlushType to telemetry and
+  // reset the count.
+  void PingReqsPerFlushTelemetry(FlushType aFlushType);
+
+  // Send the current non-zero number of style and layout flushes to telemetry
+  // and reset the count.
+  void PingFlushPerTickTelemetry(FlushType aFlushType);
+
+  // Send the current non-zero time spent under style and layout processing this
+  // tick to telemetry and reset the total.
+  void PingTotalMsPerTickTelemetry(FlushType aFlushType);
+
+  // Send the current per-tick telemetry for `aFlushType`.
+  void PingPerTickTelemetry(FlushType aFlushType);
+
+  LayoutFlushCount mReqsPerFlush;
+  LayoutFlushCount mFlushesPerTick;
+  LayoutSubsystemDurations mLayoutSubsystemDurationMs;
+};
+
+class AutoRecord {
+ public:
+  explicit AutoRecord(LayoutSubsystem aSubsystem);
+  AutoRecord(Data* aLayoutTelemetry, LayoutSubsystem aSubsystem);
+  ~AutoRecord();
+
+ private:
+  AutoRecord* mParentRecord;
+  Data* mLayoutTelemetry;
+  LayoutSubsystem mSubsystem;
+  TimeStamp mStartTime;
+  double mDurationMs;
+};
+
+}  // namespace layout_telemetry
+}  // namespace mozilla
+
+#endif  // !mozilla_LayoutTelemetryTools_h