Reset scroll and scale while toggling "Request desktop site"

third_party/WebKit/Source/web/WebViewImpl.cpp

 /*
  * Copyright (C) 2011, 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 61 matching lines @@
 #include "core/html/HTMLPlugInElement.h"
 #include "core/html/HTMLTextAreaElement.h"
 #include "core/input/ContextMenuAllowedScope.h"
 #include "core/input/EventHandler.h"
 #include "core/input/TouchActionUtil.h"
 #include "core/inspector/DevToolsEmulator.h"
 #include "core/layout/LayoutPart.h"
 #include "core/layout/TextAutosizer.h"
 #include "core/layout/api/LayoutViewItem.h"
 #include "core/layout/compositing/PaintLayerCompositor.h"
+#include "core/loader/DocumentLoader.h"
 #include "core/loader/FrameLoadRequest.h"
 #include "core/loader/FrameLoader.h"
 #include "core/loader/FrameLoaderStateMachine.h"
 #include "core/page/ContextMenuController.h"
 #include "core/page/ContextMenuProvider.h"
 #include "core/page/FocusController.h"
 #include "core/page/FrameTree.h"
 #include "core/page/Page.h"
 #include "core/page/PagePopupClient.h"
 #include "core/page/PointerLockController.h"
@@ skipping 3215 matching lines @@
 
   if (LocalFrameView* frame_view =
           ToLocalFrame(GetPage()->MainFrame())->View()) {
     ScrollableArea* scrollable_area =
         frame_view->LayoutViewportScrollableArea();
 
     if (!scrollable_area->GetScrollOffset().IsZero())
       scrollable_area->SetScrollOffset(ScrollOffset(), kProgrammaticScroll);
   }
 
+  if (Document* document = ToLocalFrame(GetPage()->MainFrame())->GetDocument())
+    document->Loader()->GetHistoryItem()->SetDidSaveScrollOrScaleState(false);

[aelias_OOO_until_Jul13, 2017/06/06 02:57:30]

This seems reasonable to me.  Could you add a unit test?  I suggest adding one
in WebViewTest.cpp, see for example related test
WebViewTest.HistoryResetScrollAndScaleState.

+
   GetPageScaleConstraintsSet().SetNeedsReset(true);
 }
 
 void WebViewImpl::PerformMediaPlayerAction(const WebMediaPlayerAction& action,
                                            const WebPoint& location) {
   HitTestResult result = HitTestResultForViewportPos(location);
   Node* node = result.InnerNode();
   if (!isHTMLVideoElement(*node) && !isHTMLAudioElement(*node))
     return;
 
@@ skipping 812 matching lines @@
   if (focused_frame->LocalFrameRoot() != MainFrameImpl()->GetFrame())
     return nullptr;
   return focused_frame;
 }
 
 LocalFrame* WebViewImpl::FocusedLocalFrameAvailableForIme() const {
   return ime_accept_events_ ? FocusedLocalFrameInWidget() : nullptr;
 }
 
 }  // namespace blink