Bug 1719668 - Do not force XFlush() on XRender r=jrmuizel,nical

Differential Revision: https://phabricator.services.mozilla.com/D119557

gfx/layers/ipc/ShadowLayers.cpp

@@ -586,13 +586,6 @@ bool ShadowLayerForwarder::EndTransaction(
     return true;
   }
 
-  if (!mTxn->mPaints.IsEmpty()) {
-    // With some platforms, telling the drawing backend that there will be no
-    // more drawing for this frame helps with preventing command queues from
-    // spanning across multiple frames.
-    gfxPlatform::GetPlatform()->FlushContentDrawing();
-  }
-
   MOZ_LAYERS_LOG(("[LayersForwarder] destroying buffers..."));
 
   MOZ_LAYERS_LOG(("[LayersForwarder] building transaction..."));

gfx/thebes/gfxPlatform.h

@@ -735,8 +735,6 @@ class gfxPlatform : public mozilla::layers::MemoryPressureListener {
   bool SupportsApzAutoscrolling() const;
   bool SupportsApzZooming() const;
 
-  virtual void FlushContentDrawing() {}
-
   // If a device reset has occurred, schedule any necessary paints in the
   // widget. This should only be used within nsRefreshDriver.
   virtual void SchedulePaintIfDeviceReset() {}

gfx/thebes/gfxPlatformGtk.cpp

@@ -258,12 +258,6 @@ void gfxPlatformGtk::InitWebRenderConfig() {
   gfxVars::SetUseWebRenderCompositor(feature.IsEnabled());
 }
 
-void gfxPlatformGtk::FlushContentDrawing() {
-  if (gfxVars::UseXRender()) {
-    XFlush(DefaultXDisplay());
-  }
-}
-
 void gfxPlatformGtk::InitPlatformGPUProcessPrefs() {
 #ifdef MOZ_WAYLAND
   if (IsWaylandDisplay()) {

gfx/thebes/gfxPlatformGtk.h

@@ -39,11 +39,6 @@ class gfxPlatformGtk final : public gfxPlatform {
 
   bool CreatePlatformFontList() override;
 
-  /**
-   * Calls XFlush if xrender is enabled.
-   */
-  void FlushContentDrawing() override;
-
   static int32_t GetFontScaleDPI();
   static double GetFontScaleFactor();