--- a/toolkit/components/telemetry/build_scripts/gen_process_enum.py
+++ b/toolkit/components/telemetry/build_scripts/gen_process_enum.py
@@ -15,16 +15,18 @@ import collections
 banner = """/* This file is auto-generated from Telemetry build scripts,
    see gen_process_enum.py. */
 """
 
 file_header = """\
 #ifndef mozilla_TelemetryProcessEnums_h
 #define mozilla_TelemetryProcessEnums_h
 
+#include <cstdint>
+
 namespace mozilla {
 namespace Telemetry {
 """
 
 file_footer = """
 } // namespace Telemetry
 } // namespace mozilla
 #endif // mozilla_TelemetryProcessEnums_h"""

--- a/toolkit/components/telemetry/core/Stopwatch.cpp
+++ b/toolkit/components/telemetry/core/Stopwatch.cpp
@@ -10,24 +10,23 @@
 #include "TelemetryUserInteraction.h"
 
 #include "js/MapAndSet.h"
 #include "js/WeakMap.h"
 #include "mozilla/dom/ScriptSettings.h"
 #include "mozilla/BackgroundHangMonitor.h"
 #include "mozilla/ClearOnShutdown.h"
 #include "mozilla/HangAnnotations.h"
+#include "mozilla/ProfilerMarkers.h"
 #include "mozilla/DataMutex.h"
 #include "mozilla/TimeStamp.h"
-#include "GeckoProfiler.h"
 #include "nsHashKeys.h"
 #include "nsContentUtils.h"
 #include "nsPrintfCString.h"
 #include "nsQueryObject.h"
-#include "nsRefPtrHashtable.h"
 #include "nsString.h"
 #include "xpcpublic.h"
 
 using mozilla::DataMutex;
 using mozilla::dom::AutoJSAPI;
 
 #define USER_INTERACTION_VALUE_MAX_LENGTH 50  // bytes
 

--- a/toolkit/components/telemetry/core/TelemetryCommon.h
+++ b/toolkit/components/telemetry/core/TelemetryCommon.h
@@ -1,24 +1,25 @@
 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2; -*- */
 /* 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/. */
 
 #ifndef TelemetryCommon_h__
 #define TelemetryCommon_h__
 
-#include "jsapi.h"
+#include "PLDHashTable.h"
+#include "js/RootingAPI.h"
+#include "js/TypeDecls.h"
 #include "mozilla/TypedEnumBits.h"
 #include "mozilla/TelemetryProcessEnums.h"
 #include "nsHashtablesFwd.h"
-#include "nsIScriptError.h"
 #include "nsTHashSet.h"
 #include "nsTHashtable.h"
-#include "nsHashKeys.h"
+#include "nsIScriptError.h"
 #include "nsXULAppAPI.h"
 
 namespace mozilla {
 namespace Telemetry {
 namespace Common {
 
 typedef nsTHashSet<nsCString> StringHashSet;
 

--- a/toolkit/components/telemetry/core/TelemetryEvent.cpp
+++ b/toolkit/components/telemetry/core/TelemetryEvent.cpp
@@ -1,27 +1,25 @@
 /* -*- 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/. */
 
 #include "Telemetry.h"
 #include "TelemetryEvent.h"
-#include <prtime.h>
 #include <limits>
 #include "ipc/TelemetryIPCAccumulator.h"
 #include "jsapi.h"
 #include "js/Array.h"  // JS::GetArrayLength, JS::IsArrayObject, JS::NewArrayObject
 #include "js/PropertyAndElement.h"  // JS_DefineElement, JS_DefineProperty, JS_Enumerate, JS_GetElement, JS_GetProperty, JS_GetPropertyById, JS_HasProperty
 #include "mozilla/Maybe.h"
 #include "mozilla/Services.h"
 #include "mozilla/StaticMutex.h"
 #include "mozilla/StaticPtr.h"
-#include "mozilla/Unused.h"
 #include "nsClassHashtable.h"
 #include "nsHashKeys.h"
 #include "nsIObserverService.h"
 #include "nsITelemetry.h"
 #include "nsJSUtils.h"
 #include "nsPrintfCString.h"
 #include "nsTArray.h"
 #include "nsUTF8Utils.h"

--- a/toolkit/components/telemetry/core/TelemetryEvent.h
+++ b/toolkit/components/telemetry/core/TelemetryEvent.h
@@ -7,17 +7,17 @@
 #define TelemetryEvent_h__
 
 #include <stdint.h>
 #include "js/TypeDecls.h"
 #include "mozilla/Maybe.h"
 #include "mozilla/TelemetryEventEnums.h"
 #include "mozilla/TelemetryProcessEnums.h"
 #include "nsTArray.h"
-#include "nsString.h"
+#include "nsStringFwd.h"
 
 namespace mozilla {
 namespace Telemetry {
 struct ChildEventData;
 struct EventExtraEntry;
 }  // namespace Telemetry
 }  // namespace mozilla
 

--- a/toolkit/components/telemetry/core/TelemetryOrigin.cpp
+++ b/toolkit/components/telemetry/core/TelemetryOrigin.cpp
@@ -1,18 +1,16 @@
 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* vim: set ts=2 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/. */
 
-#include "Telemetry.h"
 #include "TelemetryOrigin.h"
 
-#include "nsTHashMap.h"
 #include "nsIObserverService.h"
 #include "nsPrintfCString.h"
 #include "nsTArray.h"
 #include "TelemetryCommon.h"
 #include "TelemetryOriginEnums.h"
 
 #include "js/Array.h"               // JS::NewArrayObject
 #include "js/PropertyAndElement.h"  // JS_DefineElement, JS_DefineProperty

--- a/toolkit/components/telemetry/core/TelemetryOrigin.h
+++ b/toolkit/components/telemetry/core/TelemetryOrigin.h
@@ -2,19 +2,20 @@
 /* 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/. */
 
 #ifndef TelemetryOrigin_h__
 #define TelemetryOrigin_h__
 
 #include "TelemetryOriginEnums.h"
-#include "jsapi.h"
+#include "mozilla/MemoryReporting.h"
+#include "js/TypeDecls.h"
 #include "nsError.h"
-#include "nsString.h"
+#include "nsStringFwd.h"
 
 // This module is internal to Telemetry. It encapsulates Telemetry's
 // origin recording and storage logic. It should only be used by
 // Telemetry.cpp. These functions should not be used anywhere else.
 // For the public interface to Telemetry functionality, see Telemetry.h.
 
 namespace TelemetryOrigin {
 

--- a/toolkit/components/telemetry/core/TelemetryScalar.cpp
+++ b/toolkit/components/telemetry/core/TelemetryScalar.cpp
@@ -2,38 +2,35 @@
 /* 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/. */
 
 #include "TelemetryScalar.h"
 
 #include "geckoview/streaming/GeckoViewStreamingTelemetry.h"
-#include "ipc/TelemetryComms.h"
 #include "ipc/TelemetryIPCAccumulator.h"
 #include "js/Array.h"               // JS::GetArrayLength, JS::IsArrayObject
 #include "js/PropertyAndElement.h"  // JS_DefineProperty, JS_DefineUCProperty, JS_Enumerate, JS_GetElement, JS_GetProperty, JS_GetPropertyById, JS_HasProperty
 #include "mozilla/dom/ContentParent.h"
-#include "mozilla/dom/PContent.h"
 #include "mozilla/JSONWriter.h"
 #include "mozilla/Preferences.h"
 #include "mozilla/StaticMutex.h"
 #include "mozilla/StaticPtr.h"
+#include "mozilla/TelemetryComms.h"
 #include "mozilla/Unused.h"
 #include "nsBaseHashtable.h"
 #include "nsClassHashtable.h"
 #include "nsContentUtils.h"
-#include "nsTHashMap.h"
 #include "nsHashKeys.h"
 #include "nsITelemetry.h"
 #include "nsIVariant.h"
 #include "nsIXPConnect.h"
 #include "nsJSUtils.h"
 #include "nsPrintfCString.h"
-#include "nsThreadUtils.h"
 #include "nsVariant.h"
 #include "TelemetryScalarData.h"
 
 using mozilla::MakeUnique;
 using mozilla::Nothing;
 using mozilla::Preferences;
 using mozilla::Some;
 using mozilla::StaticAutoPtr;

--- a/toolkit/components/telemetry/core/TelemetryUserInteraction.cpp
+++ b/toolkit/components/telemetry/core/TelemetryUserInteraction.cpp
@@ -1,17 +1,15 @@
 /* -*- 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/. */
 
-#include "nsAString.h"
-#include "nsClassHashtable.h"
-#include "nsITelemetry.h"
+#include "nsString.h"
 #include "MainThreadUtils.h"
 #include "TelemetryUserInteraction.h"
 #include "TelemetryUserInteractionData.h"
 #include "TelemetryUserInteractionNameMap.h"
 #include "UserInteractionInfo.h"
 
 using mozilla::Telemetry::UserInteractionIDByNameLookup;
 

--- a/toolkit/components/telemetry/core/ipc/TelemetryIPC.h
+++ b/toolkit/components/telemetry/core/ipc/TelemetryIPC.h
@@ -1,20 +1,18 @@
 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2; -*- */
 /* 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/. */
 
 #ifndef TelemetryIPC_h__
 #define TelemetryIPC_h__
 
-#include <stdint.h>
 #include "mozilla/TelemetryProcessEnums.h"
 #include "nsTArray.h"
-#include "nsXULAppAPI.h"
 
 // This module provides the interface to accumulate Telemetry from child
 // processes. Top-level actors for different child processes types
 // (ContentParent, GPUChild) will call this for messages from their respective
 // processes.
 
 namespace mozilla {
 

--- a/toolkit/components/telemetry/core/ipc/TelemetryIPCAccumulator.cpp
+++ b/toolkit/components/telemetry/core/ipc/TelemetryIPCAccumulator.cpp
@@ -1,28 +1,26 @@
 /* -*- 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/. */
 
 #include "TelemetryIPCAccumulator.h"
 
-#include "core/TelemetryHistogram.h"
 #include "core/TelemetryScalar.h"
+#include "mozilla/TelemetryProcessEnums.h"
 #include "mozilla/dom/ContentChild.h"
 #include "mozilla/gfx/GPUParent.h"
-#include "mozilla/gfx/GPUProcessManager.h"
 #include "mozilla/net/SocketProcessChild.h"
 #include "mozilla/SchedulerGroup.h"
 #include "mozilla/StaticMutex.h"
 #include "mozilla/StaticPrefs_toolkit.h"
 #include "mozilla/StaticPtr.h"
 #include "mozilla/Unused.h"
-#include "nsComponentManagerUtils.h"
 #include "nsITimer.h"
 #include "nsThreadUtils.h"
 
 using mozilla::StaticAutoPtr;
 using mozilla::StaticMutex;
 using mozilla::StaticMutexAutoLock;
 using mozilla::TaskCategory;
 using mozilla::Telemetry::ChildEventData;

--- a/toolkit/components/telemetry/core/ipc/TelemetryIPCAccumulator.h
+++ b/toolkit/components/telemetry/core/ipc/TelemetryIPCAccumulator.h
@@ -4,17 +4,19 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #ifndef TelemetryIPCAccumulator_h__
 #define TelemetryIPCAccumulator_h__
 
 #include "mozilla/AlreadyAddRefed.h"
 #include "mozilla/Maybe.h"
 #include "nsStringFwd.h"
-#include "TelemetryComms.h"
+#include "mozilla/Telemetry.h"                // for EventExtraEntry
+#include "mozilla/TelemetryComms.h"           // for ScalarActionType, Scala...
+#include "mozilla/TelemetryHistogramEnums.h"  // for HistogramID
 
 class nsIRunnable;
 class nsITimer;
 
 namespace mozilla {
 
 class TimeStamp;
 

--- a/toolkit/components/telemetry/geckoview/streaming/GeckoViewStreamingTelemetry.h
+++ b/toolkit/components/telemetry/geckoview/streaming/GeckoViewStreamingTelemetry.h
@@ -2,20 +2,21 @@
 /* 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/. */
 
 #ifndef GeckoViewStreamingTelemetry_h__
 #define GeckoViewStreamingTelemetry_h__
 
-#include "mozilla/RefCounted.h"
+#include "mozilla/Assertions.h"
 #include "mozilla/RefPtr.h"
-#include "nsISupportsImpl.h"
-#include "nsString.h"
+#include "nsISupports.h"
+#include "nsStringFwd.h"
+#include "nsTArray.h"
 
 #include <cstdint>
 
 namespace GeckoViewStreamingTelemetry {
 
 void HistogramAccumulate(const nsCString& aName, bool aIsCategorical,
                          uint32_t aValue);
 

--- a/toolkit/components/telemetry/other/CombinedStacks.cpp
+++ b/toolkit/components/telemetry/other/CombinedStacks.cpp
@@ -5,17 +5,16 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "CombinedStacks.h"
 
 #include "jsapi.h"
 #include "js/Array.h"               // JS::NewArrayObject
 #include "js/PropertyAndElement.h"  // JS_DefineElement, JS_DefineProperty
 #include "js/String.h"
-#include "mozilla/HangAnnotations.h"
 
 namespace mozilla::Telemetry {
 
 // The maximum number of chrome hangs stacks that we're keeping.
 const size_t kMaxChromeStacksKept = 50;
 
 CombinedStacks::CombinedStacks() : CombinedStacks(kMaxChromeStacksKept) {}
 

--- a/toolkit/components/telemetry/other/ProcessedStack.h
+++ b/toolkit/components/telemetry/other/ProcessedStack.h
@@ -1,24 +1,23 @@
 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2; -*- */
 /* 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/. */
 
 #ifndef ProcessedStack_h__
 #define ProcessedStack_h__
 
-#include <string>
 #include <vector>
 
 #include "ipc/IPCMessageUtils.h"
 #include "ipc/IPCMessageUtilsSpecializations.h"
-#include "mozilla/ipc/ProtocolUtils.h"
+#include "mozilla/ipc/MessageChannel.h"
 #include "mozilla/Vector.h"
-#include "nsString.h"
+#include "nsStringFwd.h"
 #if defined(MOZ_GECKO_PROFILER)
 #  include "shared-libraries.h"
 #endif  // MOZ_GECKO_PROFILER
 
 namespace mozilla {
 namespace Telemetry {
 
 // This class represents a stack trace and the modules referenced in that trace.

--- a/toolkit/components/telemetry/other/TelemetryIOInterposeObserver.h
+++ b/toolkit/components/telemetry/other/TelemetryIOInterposeObserver.h
@@ -8,23 +8,22 @@
  * IOInterposeObserver recording statistics of main-thread I/O during execution,
  * aimed at consumption by TelemetryImpl
  */
 
 #ifndef TelemetryIOInterposeObserver_h__
 #define TelemetryIOInterposeObserver_h__
 
 #include "core/TelemetryCommon.h"
-#include "jsapi.h"
+#include "js/RootingAPI.h"
+#include "js/TypeDecls.h"
 #include "mozilla/IOInterposer.h"
 #include "nsBaseHashtable.h"
-#include "nsClassHashtable.h"
 #include "nsHashKeys.h"
 #include "nsTArray.h"
-#include "nsTHashtable.h"
 
 namespace mozilla {
 namespace Telemetry {
 
 class TelemetryIOInterposeObserver : public IOInterposeObserver {
   /** File-level statistics structure */
   struct FileStats {
     FileStats()