Enable iframe scrolling.

Turn off iframe expansion and record iframes in a composited layer.
Fix navigation by tracking iframe layers if needed.  Remove the logic to add
focused nodes to the last tracked layer as it is not needed and might add nodes
to the wrong layer.

Bug: 3219076, 3211666, 3201077, 3194321
Change-Id: Ifc0b83102438255db7e4b62ad260f50ebbdb0e50

1 files changed, 14 insertions, 3 deletions

diff --git a/WebCore/rendering/RenderLayerCompositor.cpp b/WebCore/rendering/RenderLayerCompositor.cpp
index ce80e5a..00e596b 100644
--- a/WebCore/rendering/RenderLayerCompositor.cpp
+++ b/WebCore/rendering/RenderLayerCompositor.cpp
@@ -1178,9 +1178,20 @@ bool RenderLayerCompositor::requiresCompositingForMobileSites(const RenderLayer*
         return true;
     HTMLFrameOwnerElement* ownerElement = enclosingIFrameElement();
     RenderObject* renderer = ownerElement ? ownerElement->renderer() : 0;
-    // FIXME: Disabled for now until navigation is fixed.
-    if (false && layer->isRootLayer() && renderer && renderer->isRenderIFrame())
-        return true;
+    if (layer->isRootLayer() && renderer && renderer->isRenderIFrame()) {
+        if (layer->renderer()->frame()) {
+            FrameView* view = layer->renderer()->frame()->view();
+            if (view) {
+                // Enable compositing if the frame can scroll and the contents
+                // are larger than the layout dimensions.
+                ScrollbarMode h,v;
+                view->scrollbarModes(h, v);
+                if ((h != ScrollbarAlwaysOff && view->layoutWidth() < view->contentsWidth()) ||
+                    (v != ScrollbarAlwaysOff && view->layoutHeight() < view->contentsHeight()))
+                    return true;
+            }
+        }
+    }
 #endif
 #if ENABLE(COMPOSITED_FIXED_ELEMENTS)
     // First, check if we are in an iframe, and if so bail out