[embedlite] Make EmbedLiteWindowListener::CompositingFinished more re…

…liable.

The notification was dispatched from custom compositor draw scheduling
code which was only used when EmbedLiteWindowListener::Invalidate
returned false. This means the event was not dispatched for qtmozembed's
QOpenGLWebPage which does not use offscreen rendering path. Instead of
using the custom EmbedLiteCompositorParent::RenderGL function to
dispatch finish events do it from nsIWidget::PostRender.

embedding/embedlite/embedshared/EmbedLitePuppetWidget.cpp

@@ -762,6 +762,16 @@ EmbedLitePuppetWidget::PreRender(LayerManagerComposite *aManager)
   return true;
 }
 
+void
+EmbedLitePuppetWidget::PostRender(LayerManagerComposite *aManager)
+{
+  MOZ_ASSERT(mWindow);
+  EmbedLiteWindow* window = EmbedLiteApp::GetInstance()->GetWindowByID(mWindow->GetUniqueID());
+  if (window) {
+    window->GetListener()->CompositingFinished();
+  }
+}
+
 void
 EmbedLitePuppetWidget::AddObserver(EmbedLitePuppetWidgetObserver* obs)
 {

embedding/embedlite/embedshared/EmbedLitePuppetWidget.h

@@ -169,6 +169,7 @@ class EmbedLitePuppetWidget : public nsBaseWidget
   virtual void DrawWindowOverlay(LayerManagerComposite* aManager, nsIntRect aRect) override;
 
   virtual bool PreRender(LayerManagerComposite* aManager) override;
+  virtual void PostRender(LayerManagerComposite* aManager) override;
 
   NS_IMETHOD         SetParent(nsIWidget* aNewParent) override;
   virtual nsIWidget* GetParent(void) override;

embedding/embedlite/embedthread/EmbedLiteCompositorParent.cpp

@@ -195,11 +195,6 @@ bool EmbedLiteCompositorParent::RenderGL(TimeStamp aScheduleTime)
     }
   }
 
-  EmbedLiteWindow* win = EmbedLiteApp::GetInstance()->GetWindowByID(mWindowId);
-  if (win) {
-    win->GetListener()->CompositingFinished();
-  }
-
   return false;
 }