diff --git a/layout/base/Baseline.h b/layout/base/Baseline.h
index 99ac8ca82c5b..0360d05bbada 100644
--- a/layout/base/Baseline.h
+++ b/layout/base/Baseline.h
@@ -2,8 +2,8 @@
  * 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 BaselineUtils_h___
-#define BaselineUtils_h___
+#ifndef LAYOUT_BASE_BASELINE_H_
+#define LAYOUT_BASE_BASELINE_H_
 
 #include "nsCoord.h"
 #include "mozilla/WritingModes.h"
@@ -41,4 +41,5 @@ class Baseline {
 };
 
 }  // namespace mozilla
-#endif  // BaselineUtils_h___
+
+#endif  // LAYOUT_BASE_BASELINE_H_
diff --git a/layout/base/moz.build b/layout/base/moz.build
index fbde0b4f690d..0fffbcfa1cf3 100644
--- a/layout/base/moz.build
+++ b/layout/base/moz.build
@@ -33,7 +33,6 @@ if CONFIG["MOZ_DEBUG"]:
 XPIDL_MODULE = "layout_base"
 
 EXPORTS += [
-    "Baseline.h",
     "CaretAssociationHint.h",
     "FrameProperties.h",
     "LayoutConstants.h",
@@ -73,6 +72,7 @@ EXPORTS += [
 EXPORTS.mozilla += [
     "AccessibleCaretEventHub.h",
     "ArenaObjectID.h",
+    "Baseline.h",
     "ContainStyleScopeManager.h",
     "DepthOrderedFrameList.h",
     "DisplayPortUtils.h",
diff --git a/layout/base/nsLayoutUtils.cpp b/layout/base/nsLayoutUtils.cpp
index 364a471f8475..bbd1ab8dfb28 100644
--- a/layout/base/nsLayoutUtils.cpp
+++ b/layout/base/nsLayoutUtils.cpp
@@ -29,6 +29,7 @@
 #include "MobileViewportManager.h"
 #include "mozilla/AccessibleCaretEventHub.h"
 #include "mozilla/ArrayUtils.h"
+#include "mozilla/Baseline.h"
 #include "mozilla/BasicEvents.h"
 #include "mozilla/ClearOnShutdown.h"
 #include "mozilla/DisplayPortUtils.h"
@@ -152,7 +153,6 @@
 #include "nsTransitionManager.h"
 #include "nsView.h"
 #include "nsViewManager.h"
-#include "Baseline.h"
 #include "prenv.h"
 #include "RegionBuilder.h"
 #include "RetainedDisplayListBuilder.h"
diff --git a/layout/forms/nsFieldSetFrame.cpp b/layout/forms/nsFieldSetFrame.cpp
index 6c81da64cd1f..60e796aa3dcc 100644
--- a/layout/forms/nsFieldSetFrame.cpp
+++ b/layout/forms/nsFieldSetFrame.cpp
@@ -9,6 +9,7 @@
 
 #include <algorithm>
 #include "gfxContext.h"
+#include "mozilla/Baseline.h"
 #include "mozilla/gfx/2D.h"
 #include "mozilla/Likely.h"
 #include "mozilla/PresShell.h"
@@ -24,7 +25,6 @@
 #include "nsIScrollableFrame.h"
 #include "nsLayoutUtils.h"
 #include "nsStyleConsts.h"
-#include "Baseline.h"
 
 using namespace mozilla;
 using namespace mozilla::gfx;
diff --git a/layout/forms/nsHTMLButtonControlFrame.cpp b/layout/forms/nsHTMLButtonControlFrame.cpp
index 3c19cb1f9aca..8c168aee2311 100644
--- a/layout/forms/nsHTMLButtonControlFrame.cpp
+++ b/layout/forms/nsHTMLButtonControlFrame.cpp
@@ -6,6 +6,7 @@
 
 #include "nsHTMLButtonControlFrame.h"
 
+#include "mozilla/Baseline.h"
 #include "mozilla/PresShell.h"
 #include "nsContainerFrame.h"
 #include "nsIFormControlFrame.h"
@@ -16,7 +17,6 @@
 #include "nsCSSAnonBoxes.h"
 #include "nsNameSpaceManager.h"
 #include "nsDisplayList.h"
-#include "Baseline.h"
 #include <algorithm>
 
 using namespace mozilla;
diff --git a/layout/generic/nsBlockFrame.cpp b/layout/generic/nsBlockFrame.cpp
index 49e1a54212c1..84b7cb7884d4 100644
--- a/layout/generic/nsBlockFrame.cpp
+++ b/layout/generic/nsBlockFrame.cpp
@@ -14,6 +14,7 @@
 #include "gfxContext.h"
 
 #include "mozilla/AppUnits.h"
+#include "mozilla/Baseline.h"
 #include "mozilla/ComputedStyle.h"
 #include "mozilla/DebugOnly.h"
 #include "mozilla/Maybe.h"
@@ -63,7 +64,6 @@
 #include "mozilla/ServoStyleSet.h"
 #include "mozilla/Telemetry.h"
 #include "nsFlexContainerFrame.h"
-#include "Baseline.h"
 
 #include "nsBidiPresUtils.h"
 
diff --git a/layout/generic/nsFlexContainerFrame.cpp b/layout/generic/nsFlexContainerFrame.cpp
index 0f55fe677df4..96cb8e47556b 100644
--- a/layout/generic/nsFlexContainerFrame.cpp
+++ b/layout/generic/nsFlexContainerFrame.cpp
@@ -11,6 +11,7 @@
 #include <algorithm>
 
 #include "gfxContext.h"
+#include "mozilla/Baseline.h"
 #include "mozilla/ComputedStyle.h"
 #include "mozilla/CSSOrderAwareFrameIterator.h"
 #include "mozilla/FloatingPoint.h"
@@ -27,7 +28,6 @@
 #include "nsLayoutUtils.h"
 #include "nsPlaceholderFrame.h"
 #include "nsPresContext.h"
-#include "Baseline.h"
 
 using namespace mozilla;
 using namespace mozilla::layout;
diff --git a/layout/generic/nsGridContainerFrame.cpp b/layout/generic/nsGridContainerFrame.cpp
index 6dc17c07f3d2..0bb32cbc619d 100644
--- a/layout/generic/nsGridContainerFrame.cpp
+++ b/layout/generic/nsGridContainerFrame.cpp
@@ -14,6 +14,7 @@
 #include <type_traits>
 #include "gfxContext.h"
 #include "mozilla/AutoRestore.h"
+#include "mozilla/Baseline.h"
 #include "mozilla/ComputedStyle.h"
 #include "mozilla/CSSAlignUtils.h"
 #include "mozilla/StaticPrefs_layout.h"
@@ -38,7 +39,6 @@
 #include "nsPresContext.h"
 #include "nsReadableUtils.h"
 #include "nsTableWrapperFrame.h"
-#include "Baseline.h"
 
 using namespace mozilla;
 
diff --git a/layout/generic/nsIFrame.h b/layout/generic/nsIFrame.h
index 5f78dfb61d1a..4882723f08c9 100644
--- a/layout/generic/nsIFrame.h
+++ b/layout/generic/nsIFrame.h
@@ -54,6 +54,7 @@
 #include "LayoutConstants.h"
 #include "mozilla/AspectRatio.h"
 #include "mozilla/Attributes.h"
+#include "mozilla/Baseline.h"
 #include "mozilla/EventForwards.h"
 #include "mozilla/Maybe.h"
 #include "mozilla/RelativeTo.h"
@@ -81,7 +82,6 @@
 #include "nsDisplayItemTypes.h"
 #include "nsPresContext.h"
 #include "nsTHashSet.h"
-#include "Baseline.h"
 
 #ifdef ACCESSIBILITY
 #  include "mozilla/a11y/AccTypes.h"
diff --git a/layout/tables/nsTableRowFrame.cpp b/layout/tables/nsTableRowFrame.cpp
index 0c6fc506eccb..f1ed8e85171c 100644
--- a/layout/tables/nsTableRowFrame.cpp
+++ b/layout/tables/nsTableRowFrame.cpp
@@ -5,6 +5,7 @@
 
 #include "nsTableRowFrame.h"
 
+#include "mozilla/Baseline.h"
 #include "mozilla/Maybe.h"
 #include "mozilla/PresShell.h"
 #include "nsTableRowGroupFrame.h"
@@ -25,7 +26,6 @@
 #include "nsCOMPtr.h"
 #include "nsDisplayList.h"
 #include "nsIFrameInlines.h"
-#include "Baseline.h"
 #include <algorithm>
 
 #ifdef ACCESSIBILITY