Remove obsolete enterForceCompositing function

public/web/WebWidget.h

Index: public/web/WebWidget.h
diff --git a/public/web/WebWidget.h b/public/web/WebWidget.h
index 71e5592a18a5ab41e44f3311735ac8fc5705ff09..54b00f3506d41f3f114ebfb022abf5ac6b577916 100644
--- a/public/web/WebWidget.h
+++ b/public/web/WebWidget.h
@@ -94,11 +94,6 @@ public:
     // and it may result in calls to WebWidgetClient::didInvalidateRect.
     virtual void layout() { }
 
-    // Called to toggle the WebWidget in or out of force compositing mode. This
-    // should be called before paint.
-    // FIXME: Remove this once WebPopuMenuImpl stops overriding it. crbug.com/378029
-    virtual void enterForceCompositingMode(bool enter) { }
-
     // Called to paint the rectangular region within the WebWidget
     // onto the specified canvas at (viewPort.x,viewPort.y). You MUST call
     // Layout before calling this method. It is okay to call paint