Bug 1504659 Part 1: Make RefreshVisualViewportSize allow non-APZ zooming, and call it during RefreshViewportSize. r=botond

Differential Revision: https://phabricator.services.mozilla.com/D13173

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

layout/base/MobileViewportManager.cpp

@@ -397,10 +397,6 @@ void MobileViewportManager::RefreshVisualViewportSize() {
   // This function is a subset of RefreshViewportSize, and only updates the
   // visual viewport size.
 
-  if (!gfxPrefs::APZAllowZooming()) {
-    return;
-  }
-
   ScreenIntSize displaySize = ViewAs<ScreenPixel>(
       mDisplaySize, PixelCastJustification::LayoutDeviceIsScreenForBounds);
 
@@ -476,6 +472,10 @@ void MobileViewportManager::RefreshViewportSize(bool aForceAdjustResolution) {
   if (gfxPrefs::APZAllowZooming()) {
     UpdateResolution(viewportInfo, displaySize, viewport,
                      displayWidthChangeRatio, UpdateType::ViewportSize);
+  } else {
+    // Even without zoom, we need to update that the visual viewport size
+    // has changed.
+    RefreshVisualViewportSize();
   }
   if (gfxPlatform::AsyncPanZoomEnabled()) {
     UpdateDisplayPortMargins();