WebViewImpl's hit tests should use setToShadowHostIfInUserAgentShadowRoot.

Source/web/WebViewImpl.cpp

Index: Source/web/WebViewImpl.cpp
diff --git a/Source/web/WebViewImpl.cpp b/Source/web/WebViewImpl.cpp
index 7123e7c77aacf34921d947c0b24af59ae91a6b88..3b0866ae3dd1ee4476e9a638c7b399a7f69b6d00 100644
--- a/Source/web/WebViewImpl.cpp
+++ b/Source/web/WebViewImpl.cpp
@@ -494,6 +494,7 @@ void WebViewImpl::handleMouseDown(LocalFrame& mainFrame, const WebMouseEvent& ev
     if (event.button == WebMouseEvent::ButtonLeft && m_page->mainFrame()->isLocalFrame() && !m_page->deprecatedLocalMainFrame()->view()->scrollbarAtPoint(point)) {
         point = m_page->deprecatedLocalMainFrame()->view()->windowToContents(point);
         HitTestResult result(m_page->deprecatedLocalMainFrame()->eventHandler().hitTestResultAtPoint(point));
+        result.setToShadowHostIfInUserAgentShadowRoot();
         Node* hitNode = result.innerNonSharedNode();
 
         if (!result.scrollbar() && hitNode && hitNode->renderer() && hitNode->renderer()->isEmbeddedObject()) {
@@ -1044,12 +1045,14 @@ WebRect WebViewImpl::computeBlockBounds(const WebRect& rect, bool ignoreClipping
     IntPoint point = mainFrameImpl()->frameView()->windowToContents(IntPoint(rect.x, rect.y));
     HitTestRequest::HitTestRequestType hitType = HitTestRequest::ReadOnly | HitTestRequest::Active | (ignoreClipping ? HitTestRequest::IgnoreClipping : 0);
     HitTestResult result = mainFrameImpl()->frame()->eventHandler().hitTestResultAtPoint(point, hitType, IntSize(rect.width, rect.height));
+    result.setToShadowHostIfInUserAgentShadowRoot();
 
     Node* node = result.innerNonSharedNode();
     if (!node)
         return WebRect();
 
     // Find the block type node based on the hit node.
+    // FIXME: This wants to walk composed tree with NodeRenderingTraversal::parent().
     while (node && (!node->renderer() || node->renderer()->isInline()))
         node = node->parentNode();
 
@@ -1175,6 +1178,7 @@ static Node* findCursorDefiningAncestor(Node* node, LocalFrame* frame)
             if (cursor != CURSOR_AUTO || frame->eventHandler().useHandCursor(node, node->isLink()))
                 break;
         }
+        // FIXME: This wants to walk composed tree with NodeRenderingTraversal::parent().

[Rick Byers, 2014/08/15 18:10:57]

Sorry about this - I just asked for it to be fixed in a review before I left on
vacation, but it looks like that fix got lost. 
https://codereview.chromium.org/402603005/

[Rick Byers, 2014/08/27 20:35:10]

You'll need to merge with trunk and remove this comment (already fixed).

         node = node->parentNode();
     }
 
@@ -1205,6 +1209,7 @@ Node* WebViewImpl::bestTapNode(const PlatformGestureEvent& tapEvent)
 
     // We might hit something like an image map that has no renderer on it
     // Walk up the tree until we have a node with an attached renderer
+    // FIXME: This wants to walk composed tree with NodeRenderingTraversal::parent().

[Rick Byers, 2014/08/27 20:35:10]

ditto

     while (bestTouchNode && !bestTouchNode->renderer())
         bestTouchNode = bestTouchNode->parentNode();
 
@@ -1221,6 +1226,7 @@ Node* WebViewImpl::bestTapNode(const PlatformGestureEvent& tapEvent)
     // has hand cursor set.
     do {
         bestTouchNode = cursorDefiningAncestor;
+        // FIXME: This wants to walk composed tree with NodeRenderingTraversal::parent().

[Rick Byers, 2014/08/27 20:35:10]

ditto

         cursorDefiningAncestor = findCursorDefiningAncestor(bestTouchNode->parentNode(), m_page->deprecatedLocalMainFrame());
     } while (cursorDefiningAncestor && showsHandCursor(cursorDefiningAncestor, m_page->deprecatedLocalMainFrame()));
 
@@ -3867,7 +3873,9 @@ HitTestResult WebViewImpl::hitTestResultForWindowPos(const IntPoint& pos)
     if (!m_page->mainFrame()->isLocalFrame())
         return HitTestResult();
     IntPoint docPoint(m_page->deprecatedLocalMainFrame()->view()->windowToContents(pos));
-    return m_page->deprecatedLocalMainFrame()->eventHandler().hitTestResultAtPoint(docPoint, HitTestRequest::ReadOnly | HitTestRequest::Active);
+    HitTestResult result = m_page->deprecatedLocalMainFrame()->eventHandler().hitTestResultAtPoint(docPoint, HitTestRequest::ReadOnly | HitTestRequest::Active);
+    result.setToShadowHostIfInUserAgentShadowRoot();

[Rick Byers, 2014/08/15 18:10:57]

Are you sure we want this for all callers of this method?  It certainly seems
like the more reasonable default behavior for code in WebViewImpl, but I don't
know enough about each of the cases to say there won't be some regression from
this change.

[esprehn, 2014/08/16 04:14:58]

Looking at the callers of this method, and their transitive callers they all
seem to either not care about the node type, or assume that you never end up
inside UA ShadowDOM.

I think this is right.

+    return result;
 }
 
 void WebViewImpl::setTabsToLinks(bool enable)