Bug 1616245 - Use GetBounds instead of mBounds. r=jfkthame

It doesn't make sense to mix mBounds with GetClientBounds(), as the windows
widget overrides both GetBounds() and GetClientBounds(). So if we're using
GetClientBounds() for the client bounds, we should be using GetBounds() for
the bounds.

Differential Revision: https://phabricator.services.mozilla.com/D70232

--HG--
extra : moz-landing-system : lando

widget/nsBaseWidget.cpp

@@ -1449,21 +1449,22 @@ void nsBaseWidget::ResizeClient(const DesktopSize& aSize, bool aRepaint) {
   NS_ASSERTION((aSize.width >= 0), "Negative width passed to ResizeClient");
   NS_ASSERTION((aSize.height >= 0), "Negative height passed to ResizeClient");
 
+  LayoutDeviceIntRect bounds = GetBounds();
   LayoutDeviceIntRect clientBounds = GetClientBounds();
 
-  // GetClientBounds and mBounds are device pixels; scale back to desktop pixels
+  // GetClientBounds and GetBounds are device pixels; scale back to desktop pixels
   // if that's what this widget uses for the Move/Resize APIs
   if (BoundsUseDesktopPixels()) {
     DesktopSize desktopDelta =
-        (LayoutDeviceIntSize(mBounds.Width(), mBounds.Height()) -
+        (LayoutDeviceIntSize(bounds.Width(), bounds.Height()) -
          clientBounds.Size()) /
         GetDesktopToDeviceScale();
     Resize(aSize.width + desktopDelta.width, aSize.height + desktopDelta.height,
            aRepaint);
   } else {
     LayoutDeviceSize layoutSize = aSize * GetDesktopToDeviceScale();
-    Resize(mBounds.Width() + (layoutSize.width - clientBounds.Width()),
-           mBounds.Height() + (layoutSize.height - clientBounds.Height()),
+    Resize(bounds.Width() + (layoutSize.width - clientBounds.Width()),
+           bounds.Height() + (layoutSize.height - clientBounds.Height()),
            aRepaint);
   }
 }
@@ -1472,6 +1473,7 @@ void nsBaseWidget::ResizeClient(const DesktopRect& aRect, bool aRepaint) {
   NS_ASSERTION((aRect.Width() >= 0), "Negative width passed to ResizeClient");
   NS_ASSERTION((aRect.Height() >= 0), "Negative height passed to ResizeClient");
 
+  LayoutDeviceIntRect bounds = GetBounds();
   LayoutDeviceIntRect clientBounds = GetClientBounds();
   LayoutDeviceIntPoint clientOffset = GetClientOffset();
   DesktopToLayoutDeviceScale scale = GetDesktopToDeviceScale();
@@ -1479,7 +1481,7 @@ void nsBaseWidget::ResizeClient(const DesktopRect& aRect, bool aRepaint) {
   if (BoundsUseDesktopPixels()) {
     DesktopPoint desktopOffset = clientOffset / scale;
     DesktopSize desktopDelta =
-        (LayoutDeviceIntSize(mBounds.Width(), mBounds.Height()) -
+        (LayoutDeviceIntSize(bounds.Width(), bounds.Height()) -
          clientBounds.Size()) /
         scale;
     Resize(aRect.X() - desktopOffset.x, aRect.Y() - desktopOffset.y,
@@ -1488,8 +1490,8 @@ void nsBaseWidget::ResizeClient(const DesktopRect& aRect, bool aRepaint) {
   } else {
     LayoutDeviceRect layoutRect = aRect * scale;
     Resize(layoutRect.X() - clientOffset.x, layoutRect.Y() - clientOffset.y,
-           layoutRect.Width() + mBounds.Width() - clientBounds.Width(),
-           layoutRect.Height() + mBounds.Height() - clientBounds.Height(),
+           layoutRect.Width() + bounds.Width() - clientBounds.Width(),
+           layoutRect.Height() + bounds.Height() - clientBounds.Height(),
            aRepaint);
   }
 }