Made text inside <input> elements scrollable using touch gestures

Source/core/rendering/RenderLayer.cpp

Index: Source/core/rendering/RenderLayer.cpp
diff --git a/Source/core/rendering/RenderLayer.cpp b/Source/core/rendering/RenderLayer.cpp
index 33efe07ede69872e94fbcfd40eb1e8f44abe5cb6..9400141a9d9ae7fbe8e53e6c24028a446ebd6796 100644
--- a/Source/core/rendering/RenderLayer.cpp
+++ b/Source/core/rendering/RenderLayer.cpp
@@ -1322,6 +1322,9 @@ bool RenderLayer::userInputScrollable(ScrollbarOrientation orientation) const
     RenderBox* box = renderBox();
     ASSERT(box);
 
+    if (box->isTextField())

[tdanderson, 2013/08/08 20:01:16]

I would re-write as:

if (box->isTextField())
    return orientation == HorizontalScrollbar;

since vertical scrolling of text fields is not possible.

Also (as you mentioned to me in person) a follow-up patch to rename
ScrollbarOrientation to ScrollOrientation may be in order, since elements such
as text fields or divs may in fact be scrollable in a certain direction but not
have any scrollbars.

[bokan, 2013/08/12 16:19:29]

Done.

+        return true;
+
     EOverflow overflowStyle = (orientation == HorizontalScrollbar) ?
         renderer()->style()->overflowX() : renderer()->style()->overflowY();
     return (overflowStyle == OSCROLL || overflowStyle == OAUTO || overflowStyle == OOVERLAY);
@@ -1950,6 +1953,10 @@ void RenderLayer::convertToLayerCoords(const RenderLayer* ancestorLayer, LayoutR
 
 bool RenderLayer::usesCompositedScrolling() const
 {
+    // Scroll textfields on the main thread so we get appropriate touch gesture propagation

[tdanderson, 2013/08/08 20:01:16]

Add a period at the end of the comment.

[bokan, 2013/08/12 16:19:29]

Done.

+    if (renderBox() && renderBox()->isTextField())

[tdanderson, 2013/08/08 20:01:16]

Are you sure that usesCompositedScrolling() is called every time there is a
user-generated scroll event (fling or otherwise) originating in a text field?

[bokan, 2013/08/12 16:19:29]

It's called when a frame has its layout updated to compute which portions of the
page should be scrolled on the main thread/impl thread.

+        return false;
+
     return isComposited() && backing()->scrollingLayer();
 }