Fix fullscreen elements in pinch viewport mode.

Source/core/page/scrolling/ScrollingCoordinator.cpp

Index: Source/core/page/scrolling/ScrollingCoordinator.cpp
diff --git a/Source/core/page/scrolling/ScrollingCoordinator.cpp b/Source/core/page/scrolling/ScrollingCoordinator.cpp
index a0ef870fad59d9896b57570a6e806bd48bd87d5c..08b970f4ebf09cc52b4c693ca42b500b70eaf11d 100644
--- a/Source/core/page/scrolling/ScrollingCoordinator.cpp
+++ b/Source/core/page/scrolling/ScrollingCoordinator.cpp
@@ -158,13 +158,25 @@ void ScrollingCoordinator::updateAfterCompositingChangeIfNeeded()
     // The mainFrame view doesn't get included in the FrameTree below, so we
     // update its size separately.
     if (WebLayer* scrollingWebLayer = frameView ? toWebLayer(frameView->layerForScrolling()) : 0) {
-        // If there is a fullscreen element, set the scroll bounds to empty so the main frame won't scroll.
+        // If there is a non-root fullscreen element, prevent the main frame
+        // from scrolling.
         Document* mainFrameDocument = m_page->deprecatedLocalMainFrame()->document();
         Element* fullscreenElement = Fullscreen::fullscreenElementFrom(*mainFrameDocument);
-        if (fullscreenElement && fullscreenElement != mainFrameDocument->documentElement())
-            scrollingWebLayer->setBounds(IntSize());
-        else
-            scrollingWebLayer->setBounds(frameView->contentsSize());
+        if (fullscreenElement && fullscreenElement != mainFrameDocument->documentElement()) {
+            if (m_page->settings().pinchVirtualViewportEnabled()) {
+                scrollingWebLayer->setUserScrollable(false, false);
+                toWebLayer(m_page->frameHost().pinchViewport().innerViewportScrollLayer())->setUserScrollable(false, false);

[Rick Byers, 2014/10/09 14:28:52]

ScrollView::setScrollbarModes can override this.  Are you sure it can never be
called when there is a fullscreen element?  Perhaps it would be better to have a
single code path that calls setUserScrollable that considers both the scrollbar
state and fullscreen mode, then call that here and from
ScrollView::setScrollbarModes?

[aelias_OOO_until_Jul13, 2014/10/10 00:58:50]

Good point.  I overrode the userInputScrollable getter in FrameView to check
whether we're fullscreen, since all the callers do an update based on that.

+            } else {
+                scrollingWebLayer->setBounds(IntSize());
+            }
+        } else {
+            if (m_page->settings().pinchVirtualViewportEnabled()) {
+                scrollingWebLayer->setUserScrollable(frameView->userInputScrollable(HorizontalScrollbar), frameView->userInputScrollable(VerticalScrollbar));
+                toWebLayer(m_page->frameHost().pinchViewport().innerViewportScrollLayer())->setUserScrollable(true, true);
+            } else {
+                scrollingWebLayer->setBounds(frameView->contentsSize());
+            }
+        }
     }
 
     const FrameTree& tree = m_page->mainFrame()->tree();