Tie scroll anchoring adjustments to frame lifecycle instead of layout.

third_party/WebKit/Source/web/tests/VisualViewportTest.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/frame/VisualViewport.h"
 
 #include "core/dom/Document.h"
 #include "core/frame/FrameHost.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
@@ skipping 1979 matching lines @@
 
   initializeWithDesktopSettings();
   webViewImpl()->resize(IntSize(800, 600));
 
   registerMockedHttpURLLoad("icb-relative-content.html");
   navigateTo(m_baseURL + "icb-relative-content.html");
 
   FrameView& frameView = *webViewImpl()->mainFrameImpl()->frameView();
   frameView.layoutViewportScrollableArea()->setScrollOffset(
       ScrollOffset(700, 500), ProgrammaticScroll);
+  webViewImpl()->updateAllLifecyclePhases();

[ymalik, 2016/10/13 13:05:40]

Why did we need to add this?

[skobes, 2016/10/13 17:21:37]

The programmatic scroll clears the anchor node.  If we don't finish the frame
here, the layout that happens during WebViewImpl::resize won't compute a new
one.

I think that's the correct behavior - if the page sets scrollTop in the same
frame as the anchor node moves, the programmatic scroll should "win".

[ymalik, 2016/10/13 17:53:19]

Acknowledged.

 
   webViewImpl()->resize(IntSize(800, 300));
   EXPECT_SIZE_EQ(ScrollOffset(700, 200),
                  frameView.layoutViewportScrollableArea()->scrollOffset());
 
   RuntimeEnabledFeatures::setScrollAnchoringEnabled(wasScrollAnchoringEnabled);
 }
 
 // Ensure that resize anchoring as happens when top controls hide/show affects
 // the scrollable area that's currently set as the root scroller.
@@ skipping 55 matching lines @@
   webViewImpl()->resize(IntSize(600, 800));
 
   EXPECT_SIZE_EQ(ScrollOffset(),
                  frameView.layoutViewportScrollableArea()->scrollOffset());
   EXPECT_EQ(600, scroller->scrollTop());
 
   RuntimeEnabledFeatures::setSetRootScrollerEnabled(wasRootScrollerEnabled);
 }
 
 }  // namespace