Add DidSaveScrollOrScaleState flag to prevent restoreScrollPositionAndViewState restore from default

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

Index: third_party/WebKit/Source/core/loader/FrameLoader.cpp
diff --git a/third_party/WebKit/Source/core/loader/FrameLoader.cpp b/third_party/WebKit/Source/core/loader/FrameLoader.cpp
index 0610418fd1c887b2c6234a917927ef78991a3ac6..759d0e7cb680939bf4834bd7338cf50226966d8e 100644
--- a/third_party/WebKit/Source/core/loader/FrameLoader.cpp
+++ b/third_party/WebKit/Source/core/loader/FrameLoader.cpp
@@ -743,7 +743,7 @@ void FrameLoader::checkCompleted() {
     m_progressTracker->progressCompleted();
     // Retry restoring scroll offset since finishing loading disables content
     // size clamping.
-    restoreScrollPositionAndViewState();
+    setScrollFromNavigation(NavigationToDifferentDocument);
 
     m_loadType = FrameLoadTypeStandard;
     m_frame->domWindow()->finishedLoading();
@@ -880,14 +880,12 @@ void FrameLoader::loadInSameDocument(
 
   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.
@@ -1376,6 +1374,11 @@ 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() ||