diff --git a/dom/events/ContentEventHandler.cpp b/dom/events/ContentEventHandler.cpp
index 063c890b98a..80f581265f6 100644
--- a/dom/events/ContentEventHandler.cpp
+++ b/dom/events/ContentEventHandler.cpp
@@ -1176,7 +1176,7 @@ ContentEventHandler::OnQueryCharacterAtPoint(WidgetQueryContentEvent* aEvent)
   nsPoint ptInTarget = ptInRoot + rootFrame->GetOffsetToCrossDoc(targetFrame);
   int32_t rootAPD = rootFrame->PresContext()->AppUnitsPerDevPixel();
   int32_t targetAPD = targetFrame->PresContext()->AppUnitsPerDevPixel();
-  ptInTarget = ptInTarget.ConvertAppUnits(rootAPD, targetAPD);
+  ptInTarget = ptInTarget.ScaleToOtherAppUnits(rootAPD, targetAPD);
 
   nsTextFrame* textframe = static_cast<nsTextFrame*>(targetFrame);
   nsIFrame::ContentOffsets contentOffsets =
diff --git a/dom/plugins/base/nsPluginInstanceOwner.cpp b/dom/plugins/base/nsPluginInstanceOwner.cpp
index c7f99883f5e..8f9534c9f97 100644
--- a/dom/plugins/base/nsPluginInstanceOwner.cpp
+++ b/dom/plugins/base/nsPluginInstanceOwner.cpp
@@ -1307,7 +1307,7 @@ GetOffsetRootContent(nsIFrame* aFrame)
       int32_t newAPD = f ? f->PresContext()->AppUnitsPerDevPixel() : 0;
       if (!f || newAPD != currAPD) {
         // Convert docOffset to the right APD and add it to offset.
-        offset += docOffset.ConvertAppUnits(currAPD, apd);
+        offset += docOffset.ScaleToOtherAppUnits(currAPD, apd);
         docOffset.x = docOffset.y = 0;
       }
       currAPD = newAPD;
@@ -1315,7 +1315,7 @@ GetOffsetRootContent(nsIFrame* aFrame)
     }
   }
 
-  offset += docOffset.ConvertAppUnits(currAPD, apd);
+  offset += docOffset.ScaleToOtherAppUnits(currAPD, apd);
 
   return offset;
 }
diff --git a/gfx/src/nsPoint.h b/gfx/src/nsPoint.h
index 718db99264a..4a621d4ceda 100644
--- a/gfx/src/nsPoint.h
+++ b/gfx/src/nsPoint.h
@@ -32,7 +32,7 @@ struct nsPoint : public mozilla::gfx::BasePoint<nscoord, nsPoint> {
    * @param aToAPP the APP to scale to
    */
   MOZ_WARN_UNUSED_RESULT inline nsPoint
-    ConvertAppUnits(int32_t aFromAPP, int32_t aToAPP) const;
+    ScaleToOtherAppUnits(int32_t aFromAPP, int32_t aToAPP) const;
 };
 
 // nsIntPoint represents a point in one of the types of pixels.
@@ -65,7 +65,7 @@ nsPoint::ToNearestPixels(nscoord aAppUnitsPerPixel) const
 }
 
 inline nsPoint
-nsPoint::ConvertAppUnits(int32_t aFromAPP, int32_t aToAPP) const
+nsPoint::ScaleToOtherAppUnits(int32_t aFromAPP, int32_t aToAPP) const
 {
   if (aFromAPP != aToAPP) {
     nsPoint point;
diff --git a/gfx/src/nsRect.h b/gfx/src/nsRect.h
index 08f555c3ee0..8cbe64add92 100644
--- a/gfx/src/nsRect.h
+++ b/gfx/src/nsRect.h
@@ -144,9 +144,9 @@ struct NS_GFX nsRect :
    * @note this can turn an empty rectangle into a non-empty rectangle
    */
   MOZ_WARN_UNUSED_RESULT inline nsRect
-    ConvertAppUnitsRoundOut(int32_t aFromAPP, int32_t aToAPP) const;
+    ScaleToOtherAppUnitsRoundOut(int32_t aFromAPP, int32_t aToAPP) const;
   MOZ_WARN_UNUSED_RESULT inline nsRect
-    ConvertAppUnitsRoundIn(int32_t aFromAPP, int32_t aToAPP) const;
+    ScaleToOtherAppUnitsRoundIn(int32_t aFromAPP, int32_t aToAPP) const;
 
   inline nsIntRect ScaleToNearestPixels(float aXScale, float aYScale,
                                         nscoord aAppUnitsPerPixel) const;
@@ -207,7 +207,7 @@ struct NS_GFX nsIntRect :
  */
 
 inline nsRect
-nsRect::ConvertAppUnitsRoundOut(int32_t aFromAPP, int32_t aToAPP) const
+nsRect::ScaleToOtherAppUnitsRoundOut(int32_t aFromAPP, int32_t aToAPP) const
 {
   if (aFromAPP == aToAPP) {
     return *this;
@@ -225,7 +225,7 @@ nsRect::ConvertAppUnitsRoundOut(int32_t aFromAPP, int32_t aToAPP) const
 }
 
 inline nsRect
-nsRect::ConvertAppUnitsRoundIn(int32_t aFromAPP, int32_t aToAPP) const
+nsRect::ScaleToOtherAppUnitsRoundIn(int32_t aFromAPP, int32_t aToAPP) const
 {
   if (aFromAPP == aToAPP) {
     return *this;
diff --git a/gfx/src/nsRegion.cpp b/gfx/src/nsRegion.cpp
index e5917c7b818..5c664567610 100644
--- a/gfx/src/nsRegion.cpp
+++ b/gfx/src/nsRegion.cpp
@@ -639,7 +639,7 @@ nsRegion& nsRegion::Transform (const gfx3DMatrix &aTransform)
 }
 
 
-nsRegion nsRegion::ConvertAppUnitsRoundOut (int32_t aFromAPP, int32_t aToAPP) const
+nsRegion nsRegion::ScaleToOtherAppUnitsRoundOut (int32_t aFromAPP, int32_t aToAPP) const
 {
   if (aFromAPP == aToAPP) {
     return *this;
@@ -650,7 +650,7 @@ nsRegion nsRegion::ConvertAppUnitsRoundOut (int32_t aFromAPP, int32_t aToAPP) co
   pixman_box32_t *boxes = pixman_region32_rectangles(&region.mImpl, &n);
   for (int i=0; i<n; i++) {
     nsRect rect = BoxToRect(boxes[i]);
-    rect = rect.ConvertAppUnitsRoundOut(aFromAPP, aToAPP);
+    rect = rect.ScaleToOtherAppUnitsRoundOut(aFromAPP, aToAPP);
     boxes[i] = RectToBox(rect);
   }
 
@@ -663,7 +663,7 @@ nsRegion nsRegion::ConvertAppUnitsRoundOut (int32_t aFromAPP, int32_t aToAPP) co
   return region;
 }
 
-nsRegion nsRegion::ConvertAppUnitsRoundIn (int32_t aFromAPP, int32_t aToAPP) const
+nsRegion nsRegion::ScaleToOtherAppUnitsRoundIn (int32_t aFromAPP, int32_t aToAPP) const
 {
   if (aFromAPP == aToAPP) {
     return *this;
@@ -674,7 +674,7 @@ nsRegion nsRegion::ConvertAppUnitsRoundIn (int32_t aFromAPP, int32_t aToAPP) con
   pixman_box32_t *boxes = pixman_region32_rectangles(&region.mImpl, &n);
   for (int i=0; i<n; i++) {
     nsRect rect = BoxToRect(boxes[i]);
-    rect = rect.ConvertAppUnitsRoundIn(aFromAPP, aToAPP);
+    rect = rect.ScaleToOtherAppUnitsRoundIn(aFromAPP, aToAPP);
     boxes[i] = RectToBox(rect);
   }
 
diff --git a/gfx/src/nsRegion.h b/gfx/src/nsRegion.h
index 04ea8cc7ac8..632398d62eb 100644
--- a/gfx/src/nsRegion.h
+++ b/gfx/src/nsRegion.h
@@ -288,15 +288,15 @@ public:
 
   /**
    * Return this region scaled to a different appunits per pixel (APP) ratio.
-   * This applies nsRect::ConvertAppUnitsRoundOut/In to each rect of the region.
+   * This applies nsRect::ScaleToOtherAppUnitsRoundOut/In to each rect of the region.
    * @param aFromAPP the APP to scale from
    * @param aToAPP the APP to scale to
    * @note this can turn an empty region into a non-empty region
    */
   MOZ_WARN_UNUSED_RESULT nsRegion
-    ConvertAppUnitsRoundOut (int32_t aFromAPP, int32_t aToAPP) const;
+    ScaleToOtherAppUnitsRoundOut (int32_t aFromAPP, int32_t aToAPP) const;
   MOZ_WARN_UNUSED_RESULT nsRegion
-    ConvertAppUnitsRoundIn (int32_t aFromAPP, int32_t aToAPP) const;
+    ScaleToOtherAppUnitsRoundIn (int32_t aFromAPP, int32_t aToAPP) const;
   nsRegion& ScaleRoundOut(float aXScale, float aYScale);
   nsRegion& ScaleInverseRoundOut(float aXScale, float aYScale);
   nsRegion& Transform (const gfx3DMatrix &aTransform);
diff --git a/gfx/src/nsSize.h b/gfx/src/nsSize.h
index f74512c7a66..f710d985a9a 100644
--- a/gfx/src/nsSize.h
+++ b/gfx/src/nsSize.h
@@ -32,7 +32,7 @@ struct nsSize : public mozilla::gfx::BaseSize<nscoord, nsSize> {
    * @param aToAPP the APP to scale to
    */
   MOZ_WARN_UNUSED_RESULT inline nsSize
-    ConvertAppUnits(int32_t aFromAPP, int32_t aToAPP) const;
+    ScaleToOtherAppUnits(int32_t aFromAPP, int32_t aToAPP) const;
 };
 
 struct nsIntSize : public mozilla::gfx::BaseSize<int32_t, nsIntSize> {
@@ -64,7 +64,7 @@ nsSize::ToNearestPixels(nscoord aAppUnitsPerPixel) const
 }
 
 inline nsSize
-nsSize::ConvertAppUnits(int32_t aFromAPP, int32_t aToAPP) const {
+nsSize::ScaleToOtherAppUnits(int32_t aFromAPP, int32_t aToAPP) const {
   if (aFromAPP != aToAPP) {
     nsSize size;
     size.width = NSToCoordRound(NSCoordScale(width, aFromAPP, aToAPP));
diff --git a/layout/base/nsDisplayList.cpp b/layout/base/nsDisplayList.cpp
index ddf07257fc2..a0058b3607f 100644
--- a/layout/base/nsDisplayList.cpp
+++ b/layout/base/nsDisplayList.cpp
@@ -4887,7 +4887,7 @@ nsRect nsDisplayZoom::GetBounds(nsDisplayListBuilder* aBuilder, bool* aSnap)
 {
   nsRect bounds = nsDisplaySubDocument::GetBounds(aBuilder, aSnap);
   *aSnap = false;
-  return bounds.ConvertAppUnitsRoundOut(mAPD, mParentAPD);
+  return bounds.ScaleToOtherAppUnitsRoundOut(mAPD, mParentAPD);
 }
 
 void nsDisplayZoom::HitTest(nsDisplayListBuilder *aBuilder,
@@ -4899,10 +4899,10 @@ void nsDisplayZoom::HitTest(nsDisplayListBuilder *aBuilder,
   // A 1x1 rect indicates we are just hit testing a point, so pass down a 1x1
   // rect as well instead of possibly rounding the width or height to zero.
   if (aRect.width == 1 && aRect.height == 1) {
-    rect.MoveTo(aRect.TopLeft().ConvertAppUnits(mParentAPD, mAPD));
+    rect.MoveTo(aRect.TopLeft().ScaleToOtherAppUnits(mParentAPD, mAPD));
     rect.width = rect.height = 1;
   } else {
-    rect = aRect.ConvertAppUnitsRoundOut(mParentAPD, mAPD);
+    rect = aRect.ScaleToOtherAppUnitsRoundOut(mParentAPD, mAPD);
   }
   mList.HitTest(aBuilder, rect, aState, aOutFrames);
 }
@@ -4914,11 +4914,11 @@ bool nsDisplayZoom::ComputeVisibility(nsDisplayListBuilder *aBuilder,
   nsRegion visibleRegion;
   // mVisibleRect has been clipped to GetClippedBounds
   visibleRegion.And(*aVisibleRegion, mVisibleRect);
-  visibleRegion = visibleRegion.ConvertAppUnitsRoundOut(mParentAPD, mAPD);
+  visibleRegion = visibleRegion.ScaleToOtherAppUnitsRoundOut(mParentAPD, mAPD);
   nsRegion originalVisibleRegion = visibleRegion;
 
   nsRect transformedVisibleRect =
-    mVisibleRect.ConvertAppUnitsRoundOut(mParentAPD, mAPD);
+    mVisibleRect.ScaleToOtherAppUnitsRoundOut(mParentAPD, mAPD);
   bool retval;
   // If we are to generate a scrollable layer we call
   // nsDisplaySubDocument::ComputeVisibility to make the necessary adjustments
@@ -4937,7 +4937,7 @@ bool nsDisplayZoom::ComputeVisibility(nsDisplayListBuilder *aBuilder,
   // removed = originalVisibleRegion - visibleRegion
   removed.Sub(originalVisibleRegion, visibleRegion);
   // Convert removed region to parent appunits.
-  removed = removed.ConvertAppUnitsRoundIn(mAPD, mParentAPD);
+  removed = removed.ScaleToOtherAppUnitsRoundIn(mAPD, mParentAPD);
   // aVisibleRegion = aVisibleRegion - removed (modulo any simplifications
   // SubtractFromVisibleRegion does)
   aBuilder->SubtractFromVisibleRegion(aVisibleRegion, removed);
diff --git a/layout/base/nsLayoutUtils.cpp b/layout/base/nsLayoutUtils.cpp
index f08d9c6d795..2056ce90bc6 100644
--- a/layout/base/nsLayoutUtils.cpp
+++ b/layout/base/nsLayoutUtils.cpp
@@ -2066,7 +2066,7 @@ nsLayoutUtils::GetEventCoordinatesRelativeTo(nsIWidget* aWidget,
   // is in.
   int32_t rootAPD = rootFrame->PresContext()->AppUnitsPerDevPixel();
   int32_t localAPD = aFrame->PresContext()->AppUnitsPerDevPixel();
-  widgetToView = widgetToView.ConvertAppUnits(rootAPD, localAPD);
+  widgetToView = widgetToView.ScaleToOtherAppUnits(rootAPD, localAPD);
 
   /* If we encountered a transform, we can't do simple arithmetic to figure
    * out how to convert back to aFrame's coordinates and must use the CTM.
diff --git a/layout/base/nsPresShell.cpp b/layout/base/nsPresShell.cpp
index 06b146fb640..72e19f283d6 100644
--- a/layout/base/nsPresShell.cpp
+++ b/layout/base/nsPresShell.cpp
@@ -3749,7 +3749,7 @@ PresShell::ScrollFrameRectIntoView(nsIFrame*                aFrame,
       if (parent) {
         int32_t APD = container->PresContext()->AppUnitsPerDevPixel();
         int32_t parentAPD = parent->PresContext()->AppUnitsPerDevPixel();
-        rect = rect.ConvertAppUnitsRoundOut(APD, parentAPD);
+        rect = rect.ScaleToOtherAppUnitsRoundOut(APD, parentAPD);
         rect += extraOffset;
       }
     }
@@ -5735,7 +5735,7 @@ PresShell::ProcessSynthMouseMoveEvent(bool aFromScroll)
     nsIFrame* frame = view->GetFrame();
     NS_ASSERTION(frame, "floating views can't be anonymous");
     viewAPD = frame->PresContext()->AppUnitsPerDevPixel();
-    refpoint = mMouseLocation.ConvertAppUnits(APD, viewAPD);
+    refpoint = mMouseLocation.ScaleToOtherAppUnits(APD, viewAPD);
     refpoint -= view->GetOffsetTo(rootView);
     refpoint += view->ViewToWidgetOffset();
   }
@@ -5869,7 +5869,7 @@ PresShell::MarkImagesInSubtreeVisible(nsIFrame* aFrame, const nsRect& aRect)
       } else {
         rect.MoveBy(-aFrame->GetContentRectRelativeToSelf().TopLeft());
       }
-      rect = rect.ConvertAppUnitsRoundOut(
+      rect = rect.ScaleToOtherAppUnitsRoundOut(
         aFrame->PresContext()->AppUnitsPerDevPixel(),
         presShell->GetPresContext()->AppUnitsPerDevPixel());
 
@@ -8639,7 +8639,7 @@ PresShell::GetCurrentItemAndPositionForElement(nsIDOMElement *aCurrentEl,
           nsIFrame* f = do_QueryFrame(scrollFrame);
           int32_t APD = presContext->AppUnitsPerDevPixel();
           int32_t scrollAPD = f->PresContext()->AppUnitsPerDevPixel();
-          scrollAmount = scrollAmount.ConvertAppUnits(scrollAPD, APD);
+          scrollAmount = scrollAmount.ScaleToOtherAppUnits(scrollAPD, APD);
           if (extra > scrollAmount.height) {
             extra = scrollAmount.height;
           }
diff --git a/layout/generic/nsFrame.cpp b/layout/generic/nsFrame.cpp
index 8afbc6e2169..b881a9a4cfb 100644
--- a/layout/generic/nsFrame.cpp
+++ b/layout/generic/nsFrame.cpp
@@ -4750,7 +4750,7 @@ nsIFrame::GetOffsetToCrossDoc(const nsIFrame* aOther, const int32_t aAPD) const
       int32_t newAPD = f ? f->PresContext()->AppUnitsPerDevPixel() : 0;
       if (!f || newAPD != currAPD) {
         // Convert docOffset to the right APD and add it to offset.
-        offset += docOffset.ConvertAppUnits(currAPD, aAPD);
+        offset += docOffset.ScaleToOtherAppUnits(currAPD, aAPD);
         docOffset.x = docOffset.y = 0;
       }
       currAPD = newAPD;
@@ -4758,7 +4758,7 @@ nsIFrame::GetOffsetToCrossDoc(const nsIFrame* aOther, const int32_t aAPD) const
     }
   }
   if (f == aOther) {
-    offset += docOffset.ConvertAppUnits(currAPD, aAPD);
+    offset += docOffset.ScaleToOtherAppUnits(currAPD, aAPD);
   } else {
     // Looks like aOther wasn't an ancestor of |this|.  So now we have
     // the root-document-relative position of |this| in |offset|. Subtract the
diff --git a/layout/generic/nsSubDocumentFrame.cpp b/layout/generic/nsSubDocumentFrame.cpp
index 31abff98c13..84b15e07298 100644
--- a/layout/generic/nsSubDocumentFrame.cpp
+++ b/layout/generic/nsSubDocumentFrame.cpp
@@ -411,7 +411,7 @@ nsSubDocumentFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
     // get the dirty rect relative to the root frame of the subdoc
     dirty = aDirtyRect + GetOffsetToCrossDoc(subdocRootFrame);
     // and convert into the appunits of the subdoc
-    dirty = dirty.ConvertAppUnitsRoundOut(parentAPD, subdocAPD);
+    dirty = dirty.ScaleToOtherAppUnitsRoundOut(parentAPD, subdocAPD);
 
     if (nsIFrame* rootScrollFrame = presShell->GetRootScrollFrame()) {
       if (gfxPrefs::LayoutUseContainersForRootFrames()) {
@@ -500,7 +500,7 @@ nsSubDocumentFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
       nsRect bounds = GetContentRectRelativeToSelf() +
         aBuilder->ToReferenceFrame(this);
       if (subdocRootFrame) {
-        bounds = bounds.ConvertAppUnitsRoundOut(parentAPD, subdocAPD);
+        bounds = bounds.ScaleToOtherAppUnitsRoundOut(parentAPD, subdocAPD);
       }
 
       // If we are in print preview/page layout we want to paint the grey
diff --git a/layout/xul/nsMenuPopupFrame.cpp b/layout/xul/nsMenuPopupFrame.cpp
index f2be7f808e3..d1a8db4990d 100644
--- a/layout/xul/nsMenuPopupFrame.cpp
+++ b/layout/xul/nsMenuPopupFrame.cpp
@@ -1247,8 +1247,8 @@ nsMenuPopupFrame::SetPopupPosition(nsIFrame* aAnchorFrame, bool aIsMove, bool aS
   parentRect.MoveBy(referenceFrame->GetScreenRectInAppUnits().TopLeft());
   // In its own app units
   parentRect =
-    parentRect.ConvertAppUnitsRoundOut(rootPresContext->AppUnitsPerDevPixel(),
-                                       presContext->AppUnitsPerDevPixel());
+    parentRect.ScaleToOtherAppUnitsRoundOut(rootPresContext->AppUnitsPerDevPixel(),
+                                            presContext->AppUnitsPerDevPixel());
 
   // Set the popup's size to the preferred size. Below, this size will be
   // adjusted to fit on the screen or within the content area. If the anchor
diff --git a/view/nsView.cpp b/view/nsView.cpp
index 6f9c3ea7b7f..74bed3e126e 100644
--- a/view/nsView.cpp
+++ b/view/nsView.cpp
@@ -819,7 +819,7 @@ nsPoint nsView::GetOffsetTo(const nsView* aOther, const int32_t aAPD) const
     if (newVM != currVM) {
       int32_t newAPD = newVM->AppUnitsPerDevPixel();
       if (newAPD != currAPD) {
-        offset += docOffset.ConvertAppUnits(currAPD, aAPD);
+        offset += docOffset.ScaleToOtherAppUnits(currAPD, aAPD);
         docOffset.x = docOffset.y = 0;
         currAPD = newAPD;
       }
@@ -827,7 +827,7 @@ nsPoint nsView::GetOffsetTo(const nsView* aOther, const int32_t aAPD) const
     }
     docOffset += v->GetPosition();
   }
-  offset += docOffset.ConvertAppUnits(currAPD, aAPD);
+  offset += docOffset.ScaleToOtherAppUnits(currAPD, aAPD);
 
   if (v != aOther) {
     // Looks like aOther wasn't an ancestor of |this|.  So now we have
@@ -863,7 +863,7 @@ nsPoint nsView::GetOffsetToWidget(nsIWidget* aWidget) const
   // Convert to our appunits.
   int32_t widgetAPD = widgetView->GetViewManager()->AppUnitsPerDevPixel();
   int32_t ourAPD = GetViewManager()->AppUnitsPerDevPixel();
-  pt = pt.ConvertAppUnits(widgetAPD, ourAPD);
+  pt = pt.ScaleToOtherAppUnits(widgetAPD, ourAPD);
   return pt;
 }
 
@@ -889,7 +889,7 @@ nsIWidget* nsView::GetNearestWidget(nsPoint* aOffset, const int32_t aAPD) const
     if (newVM != currVM) {
       int32_t newAPD = newVM->AppUnitsPerDevPixel();
       if (newAPD != currAPD) {
-        pt += docPt.ConvertAppUnits(currAPD, aAPD);
+        pt += docPt.ScaleToOtherAppUnits(currAPD, aAPD);
         docPt.x = docPt.y = 0;
         currAPD = newAPD;
       }
@@ -899,7 +899,7 @@ nsIWidget* nsView::GetNearestWidget(nsPoint* aOffset, const int32_t aAPD) const
   }
   if (!v) {
     if (aOffset) {
-      pt += docPt.ConvertAppUnits(currAPD, aAPD);
+      pt += docPt.ScaleToOtherAppUnits(currAPD, aAPD);
       *aOffset = pt;
     }
     return nullptr;
@@ -909,7 +909,7 @@ nsIWidget* nsView::GetNearestWidget(nsPoint* aOffset, const int32_t aAPD) const
   // We add the ViewToWidgetOffset to get the offset to the widget.
   if (aOffset) {
     docPt += v->ViewToWidgetOffset();
-    pt += docPt.ConvertAppUnits(currAPD, aAPD);
+    pt += docPt.ScaleToOtherAppUnits(currAPD, aAPD);
     *aOffset = pt;
   }
   return v->GetWidget();
@@ -931,7 +931,7 @@ nsView::GetBoundsInParentUnits() const
   }
   int32_t ourAPD = VM->AppUnitsPerDevPixel();
   int32_t parentAPD = parent->GetViewManager()->AppUnitsPerDevPixel();
-  return mDimBounds.ConvertAppUnitsRoundOut(ourAPD, parentAPD);
+  return mDimBounds.ScaleToOtherAppUnitsRoundOut(ourAPD, parentAPD);
 }
 
 nsPoint
@@ -939,8 +939,9 @@ nsView::ConvertFromParentCoords(nsPoint aPt) const
 {
   const nsView* parent = GetParent();
   if (parent) {
-    aPt = aPt.ConvertAppUnits(parent->GetViewManager()->AppUnitsPerDevPixel(),
-                              GetViewManager()->AppUnitsPerDevPixel());
+    aPt = aPt.ScaleToOtherAppUnits(
+      parent->GetViewManager()->AppUnitsPerDevPixel(),
+      GetViewManager()->AppUnitsPerDevPixel());
   }
   aPt -= GetPosition();
   return aPt;
diff --git a/view/nsViewManager.cpp b/view/nsViewManager.cpp
index f2231947aa3..fce226fe627 100644
--- a/view/nsViewManager.cpp
+++ b/view/nsViewManager.cpp
@@ -243,7 +243,7 @@ static nsRegion ConvertRegionBetweenViews(const nsRegion& aIn,
 {
   nsRegion out = aIn;
   out.MoveBy(aFromView->GetOffsetTo(aToView));
-  out = out.ConvertAppUnitsRoundOut(
+  out = out.ScaleToOtherAppUnitsRoundOut(
     aFromView->GetViewManager()->AppUnitsPerDevPixel(),
     aToView->GetViewManager()->AppUnitsPerDevPixel());
   return out;
@@ -640,7 +640,7 @@ nsViewManager::InvalidateViewNoSuppression(nsView *aView,
   damagedRect.MoveBy(aView->GetOffsetTo(displayRoot));
   int32_t rootAPD = displayRootVM->AppUnitsPerDevPixel();
   int32_t APD = AppUnitsPerDevPixel();
-  damagedRect = damagedRect.ConvertAppUnitsRoundOut(APD, rootAPD);
+  damagedRect = damagedRect.ScaleToOtherAppUnitsRoundOut(APD, rootAPD);
 
   // accumulate this rectangle in the view's dirty region, so we can
   // process it later.