Attempt scroll restoration anytime viewport size changes

Viewport size determines the scroll clamp boundaries so when it changes,
we should retry any pending scroll restoration in case it is blocked
due to clamping. This can happen when page scale changes.

Removed |FrameView::clampOffsetAtScale| as it was only ever used
with scale 1 and could be replaces with |ScrollableArea::clampScrollPosition|.

FrameView calls the restore method directly making it unnecessary for
ChromeClient to be involved.


BUG=522153

Review URL: https://codereview.chromium.org/1300393003

git-svn-id: svn://svn.chromium.org/blink/trunk@201323 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/frame/FrameView.cpp

@@ -405,8 +405,11 @@ void FrameView::setFrameRect(const IntRect& newRect)
 
     viewportSizeChanged(newRect.width() != oldRect.width(), newRect.height() != oldRect.height());
 
-    if (oldRect.size() != newRect.size() && m_frame->isMainFrame())
-        page()->frameHost().visualViewport().mainFrameDidChangeSize();
+    if (oldRect.size() != newRect.size()) {
+        if (m_frame->isMainFrame())
+            m_frame->host()->visualViewport().mainFrameDidChangeSize();
+        frame().loader().restoreScrollPositionAndViewState();
+    }
 }
 
 Page* FrameView::page() const
@@ -508,20 +511,7 @@ void FrameView::setContentsSize(const IntSize& size)
     updateScrollableAreaSet();
 
     page->chromeClient().contentsSizeChanged(m_frame.get(), size);
-}
-
-IntPoint FrameView::clampOffsetAtScale(const IntPoint& offset, float scale) const
-{
-    IntPoint maxScrollExtent(contentsSize().width() - scrollOrigin().x(), contentsSize().height() - scrollOrigin().y());
-    FloatSize scaledSize = visibleContentSize();
-    if (scale)
-        scaledSize.scale(1 / scale);
-
-    IntPoint clampedOffset = offset;
-    clampedOffset = clampedOffset.shrunkTo(maxScrollExtent - expandedIntSize(scaledSize));
-    clampedOffset = clampedOffset.expandedTo(-scrollOrigin());
-
-    return clampedOffset;
+    frame().loader().restoreScrollPositionAndViewState();
 }
 
 void FrameView::adjustViewSize()
@@ -796,7 +786,7 @@ void FrameView::performPreLayoutTasks()
     lifecycle().advanceTo(DocumentLifecycle::StyleClean);
 
     if (m_frame->isMainFrame() && !m_viewportScrollableArea) {
-        ScrollableArea& visualViewport = page()->frameHost().visualViewport();
+        ScrollableArea& visualViewport = m_frame->host()->visualViewport();
         ScrollableArea* layoutViewport = layoutViewportScrollableArea();
         bool invertScrollOrder = m_frame->settings()->invertViewportScrollOrder();
         ASSERT(layoutViewport);
@@ -2193,7 +2183,7 @@ IntSize FrameView::inputEventsOffsetForEmulation() const
 
 float FrameView::inputEventsScaleFactor() const
 {
-    float pageScale = m_frame->page()->frameHost().visualViewport().scale();
+    float pageScale = m_frame->host()->visualViewport().scale();
     return pageScale * m_inputEventsScaleFactorForEmulation;
 }
 
@@ -3547,14 +3537,14 @@ FloatPoint FrameView::rootFrameToContents(const FloatPoint& windowPoint) const
 
 IntRect FrameView::viewportToContents(const IntRect& rectInViewport) const
 {
-    IntRect rectInRootFrame = page()->frameHost().visualViewport().viewportToRootFrame(rectInViewport);
+    IntRect rectInRootFrame = m_frame->host()->visualViewport().viewportToRootFrame(rectInViewport);
     IntRect frameRect = convertFromContainingWindow(rectInRootFrame);
     return frameToContents(frameRect);
 }
 
 IntPoint FrameView::viewportToContents(const IntPoint& pointInViewport) const
 {
-    IntPoint pointInRootFrame = page()->frameHost().visualViewport().viewportToRootFrame(pointInViewport);
+    IntPoint pointInRootFrame = m_frame->host()->visualViewport().viewportToRootFrame(pointInViewport);
     IntPoint pointInFrame = convertFromContainingWindow(pointInRootFrame);
     return frameToContents(pointInFrame);
 }
@@ -3563,14 +3553,14 @@ IntRect FrameView::contentsToViewport(const IntRect& rectInContents) const
 {
     IntRect rectInFrame = contentsToFrame(rectInContents);
     IntRect rectInRootFrame = convertToContainingWindow(rectInFrame);
-    return page()->frameHost().visualViewport().rootFrameToViewport(rectInRootFrame);
+    return m_frame->host()->visualViewport().rootFrameToViewport(rectInRootFrame);
 }
 
 IntPoint FrameView::contentsToViewport(const IntPoint& pointInContents) const
 {
     IntPoint pointInFrame = contentsToFrame(pointInContents);
     IntPoint pointInRootFrame = convertToContainingWindow(pointInFrame);
-    return page()->frameHost().visualViewport().rootFrameToViewport(pointInRootFrame);
+    return m_frame->host()->visualViewport().rootFrameToViewport(pointInRootFrame);
 }
 
 IntRect FrameView::contentsToScreen(const IntRect& rect) const
@@ -3585,12 +3575,12 @@ IntRect FrameView::soonToBeRemovedContentsToUnscaledViewport(const IntRect& rect
 {
     IntRect rectInFrame = contentsToFrame(rectInContents);
     IntRect rectInRootFrame = convertToContainingWindow(rectInFrame);
-    return enclosingIntRect(page()->frameHost().visualViewport().mainViewToViewportCSSPixels(rectInRootFrame));
+    return enclosingIntRect(m_frame->host()->visualViewport().mainViewToViewportCSSPixels(rectInRootFrame));
 }
 
 IntPoint FrameView::soonToBeRemovedUnscaledViewportToContents(const IntPoint& pointInViewport) const
 {
-    IntPoint pointInRootFrame = flooredIntPoint(page()->frameHost().visualViewport().viewportCSSPixelsToRootFrame(pointInViewport));
+    IntPoint pointInRootFrame = flooredIntPoint(m_frame->host()->visualViewport().viewportCSSPixelsToRootFrame(pointInViewport));
     IntPoint pointInThisFrame = convertFromContainingWindow(pointInRootFrame);
     return frameToContents(pointInThisFrame);
 }

third_party/WebKit/Source/core/frame/FrameView.h

@@ -104,7 +104,6 @@ public:
     PassRefPtrWillBeRawPtr<Scrollbar> createScrollbar(ScrollbarOrientation);
 
     void setContentsSize(const IntSize&);
-    IntPoint clampOffsetAtScale(const IntPoint& offset, float scale) const;
 
     void layout();
     bool didFirstLayout() const;

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

@@ -1114,7 +1114,7 @@ FrameLoadType FrameLoader::loadType() const
 void FrameLoader::restoreScrollPositionAndViewState()
 {
     FrameView* view = m_frame->view();
-    if (!m_frame->page() || !view || !m_currentItem || !m_stateMachine.committedFirstRealDocumentLoad())
+    if (!m_frame->page() || !view || !view->layoutViewportScrollableArea() || !m_currentItem || !m_stateMachine.committedFirstRealDocumentLoad())
         return;
 
     if (!needsHistoryItemRestore(m_loadType))
@@ -1131,7 +1131,7 @@ void FrameLoader::restoreScrollPositionAndViewState()
     //   4. ignore clamp detection if we are not restoring scroll or after load
     //      completes because that may be because the page will never reach its
     //      previous height
-    bool canRestoreWithoutClamping = view->clampOffsetAtScale(m_currentItem->scrollPoint(), 1) == m_currentItem->scrollPoint();
+    bool canRestoreWithoutClamping = view->layoutViewportScrollableArea()->clampScrollPosition(m_currentItem->scrollPoint()) == m_currentItem->scrollPoint();
     bool canRestoreWithoutAnnoyingUser = !documentLoader()->initialScrollState().wasScrolledByUser
         && (canRestoreWithoutClamping || !m_frame->isLoading() || !shouldRestoreScroll);
     if (!canRestoreWithoutAnnoyingUser)

third_party/WebKit/Source/web/ChromeClientImpl.cpp

@@ -529,8 +529,6 @@ void ChromeClientImpl::contentsSizeChanged(LocalFrame* frame, const IntSize& siz
 
     WebLocalFrameImpl* webframe = WebLocalFrameImpl::fromFrame(frame);
     webframe->didChangeContentsSize(size);
-
-    frame->loader().restoreScrollPositionAndViewState();
 }
 
 void ChromeClientImpl::pageScaleFactorChanged() const