Revert "Bug 1882358 Part 2: Make WebRenderLayerManager track widget size to detect resizes. r=nical"

This reverts commit 3904945.

Author: K4sum1

gfx/layers/wr/WebRenderLayerManager.cpp

@@ -97,7 +97,6 @@ bool WebRenderLayerManager::Initialize(
   }
 
   mWrChild = static_cast<WebRenderBridgeChild*>(bridge);
-  mHasFlushedThisChild = false;
 
   TextureFactoryIdentifier textureFactoryIdentifier;
   wr::MaybeIdNamespace idNamespace;
@@ -703,30 +702,24 @@ void WebRenderLayerManager::FlushRendering(wr::RenderReasons aReasons) {
   }
   MOZ_ASSERT(mWidget);
 
-  // If widget bounds size is different from the last flush, consider
-  // this to be a resize. It's important to use GetClientSize here,
-  // because that has extra plumbing to support initial display cases
-  // where the widget doesn't yet have real bounds.
-  LayoutDeviceIntSize widgetSize = mWidget->GetClientSize();
-  bool resizing = widgetSize != mFlushWidgetSize;
-  mFlushWidgetSize = widgetSize;
+  // If value of IsResizingNativeWidget() is nothing, we assume that resizing
+  // might happen.
+  bool resizing = mWidget && mWidget->IsResizingNativeWidget().valueOr(true);
 
   if (resizing) {
     aReasons = aReasons | wr::RenderReasons::RESIZE;
   }
 
-  // Check for the conditions where we we force a sync flush. The first
-  // flush for this child should always be sync. Resizes should be
-  // sometimes be sync. Everything else can be async.
-  if (!mHasFlushedThisChild ||
-      (resizing && (mWidget->SynchronouslyRepaintOnResize() ||
-                    StaticPrefs::layers_force_synchronous_resize()))) {
+  // Limit async FlushRendering to !resizing and Win DComp.
+  // XXX relax the limitation
+  if (WrBridge()->GetCompositorUseDComp() && !resizing) {
+    cBridge->SendFlushRenderingAsync(aReasons);
+  } else if (mWidget->SynchronouslyRepaintOnResize() ||
+             StaticPrefs::layers_force_synchronous_resize()) {
     cBridge->SendFlushRendering(aReasons);
   } else {
     cBridge->SendFlushRenderingAsync(aReasons);
   }
-
-  mHasFlushedThisChild = true;
 }
 
 void WebRenderLayerManager::WaitOnTransactionProcessed() {

gfx/layers/wr/WebRenderLayerManager.h

@@ -226,7 +226,6 @@ class WebRenderLayerManager final : public WindowRenderer {
   nsIWidget* MOZ_NON_OWNING_REF mWidget;
 
   RefPtr<WebRenderBridgeChild> mWrChild;
-  bool mHasFlushedThisChild;
 
   RefPtr<TransactionIdAllocator> mTransactionIdAllocator;
   TransactionId mLatestTransactionId;
@@ -274,8 +273,6 @@ class WebRenderLayerManager final : public WindowRenderer {
   UniquePtr<wr::DisplayListBuilder> mDLBuilder;
 
   ScrollUpdatesMap mPendingScrollUpdates;
-
-  LayoutDeviceIntSize mFlushWidgetSize;
 };
 
 }  // namespace layers