Add DidSaveScrollOrScaleState flag to prevent restoreScrollPositionAndViewState restore from default

third_party/WebKit/Source/core/loader/FrameLoader.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights
  * reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
  * Copyright (C) 2008 Alp Toker <alp@atoker.com>
  * Copyright (C) Research In Motion Limited 2009. All rights reserved.
  * Copyright (C) 2011 Kris Jordan <krisjordan@gmail.com>
  * Copyright (C) 2011 Google Inc. All rights reserved.
@@ skipping 725 matching lines @@
     client()->dispatchDidFinishLoad();
     // Finishing the load can detach the frame when running layout tests.
     if (!m_frame->client())
       return;
   }
 
   if (shouldSendCompleteNotification(m_frame, m_isNavigationHandledByClient)) {
     m_progressTracker->progressCompleted();
     // Retry restoring scroll offset since finishing loading disables content
     // size clamping.
-    restoreScrollPositionAndViewState();
+    setScrollFromNavigation(NavigationToDifferentDocument);
 
     m_loadType = FrameLoadTypeStandard;
     m_frame->domWindow()->finishedLoading();
   }
 
   Frame* parent = m_frame->tree().parent();
   if (parent && parent->isLocalFrame())
     toLocalFrame(parent)->loader().checkCompleted();
 }
 
@@ skipping 116 matching lines @@
     m_frame->domWindow()->enqueueHashchangeEvent(oldURL, url);
   }
   m_documentLoader->setIsClientRedirect(clientRedirect ==
                                         ClientRedirectPolicy::ClientRedirect);
   updateForSameDocumentNavigation(url, SameDocumentNavigationDefault, nullptr,
                                   ScrollRestorationAuto, frameLoadType,
                                   initiatingDocument);
 
   m_documentLoader->initialScrollState().wasScrolledByUser = false;
 
-  checkCompleted();

[Nate Chapin, 2017/01/26 21:25:35]

Context: I suggested removing this, because updateForSameDocumentNavigation()
will handle pulsing start/stop notifications if Frame::isLoading() is false, and
all of the logic in checkCompleted() really ought to be specific to
different-document navigations.

[majidvp, 2017/01/26 21:49:50]

Interesting. That works. Should we add a DCHECK in checkCompleted() to
document this assumption?

-
   m_frame->domWindow()->statePopped(stateObject
                                         ? std::move(stateObject)
                                         : SerializedScriptValue::nullValue());
 
   if (historyLoadType == HistorySameDocumentLoad)
-    restoreScrollPositionAndViewState();
+    setScrollFromNavigation(NavigationWithinSameDocument);
 
   // We need to scroll to the fragment whether or not a hash change occurred,
   // since the user might have scrolled since the previous navigation.
   processFragment(url, NavigationWithinSameDocument);
   takeObjectSnapshot();
 }
 
 // static
 void FrameLoader::setReferrerForFrameRequest(FrameLoadRequest& frameRequest) {
   ResourceRequest& request = frameRequest.resourceRequest();
@@ skipping 468 matching lines @@
 }
 
 bool FrameLoader::isLoadingMainFrame() const {
   return m_frame->isMainFrame();
 }
 
 FrameLoadType FrameLoader::loadType() const {
   return m_loadType;
 }
 
+void FrameLoader::setScrollFromNavigation(LoadStartType loadStartType) {
+  processFragment(m_frame->document()->url(), loadStartType);
+  restoreScrollPositionAndViewState();
+}
+
 void FrameLoader::restoreScrollPositionAndViewState() {
   FrameView* view = m_frame->view();
   if (!m_frame->page() || !view || !view->layoutViewportScrollableArea() ||
       !m_currentItem || !m_stateMachine.committedFirstRealDocumentLoad() ||
       !documentLoader()) {
     return;
   }
 
   if (!needsHistoryItemRestore(m_loadType))
     return;
@@ skipping 516 matching lines @@
                          m_documentLoader ? m_documentLoader->url() : String());
   return tracedValue;
 }
 
 inline void FrameLoader::takeObjectSnapshot() const {
   TRACE_EVENT_OBJECT_SNAPSHOT_WITH_ID("loading", "FrameLoader", this,
                                       toTracedValue());
 }
 
 }  // namespace blink