[SPInvalidation] Fix caret paint invalidation in sub frames

third_party/WebKit/Source/core/editing/FrameCaret.cpp

Index: third_party/WebKit/Source/core/editing/FrameCaret.cpp
diff --git a/third_party/WebKit/Source/core/editing/FrameCaret.cpp b/third_party/WebKit/Source/core/editing/FrameCaret.cpp
index 1a65d873c38e59ed34523d1164bfaf41cb6c35cd..7efa3856c33c9a9d7ea1fcba430a669f98ed3c3f 100644
--- a/third_party/WebKit/Source/core/editing/FrameCaret.cpp
+++ b/third_party/WebKit/Source/core/editing/FrameCaret.cpp
@@ -29,11 +29,12 @@
 #include "core/editing/Editor.h"
 #include "core/editing/SelectionEditor.h"
 #include "core/editing/commands/CompositeEditCommand.h"
+#include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Settings.h"
 #include "core/html/TextControlElement.h"
 #include "core/layout/LayoutTheme.h"
-#include "core/layout/api/LayoutViewItem.h"
+#include "core/layout/api/LayoutPartItem.h"
 #include "core/page/Page.h"
 #include "core/paint/PaintLayer.h"
 #include "public/platform/WebTraceLocation.h"
@@ -142,6 +143,13 @@ void FrameCaret::setCaretRectNeedsUpdate() {
 
   if (Page* page = m_frame->page())
     page->animator().scheduleVisualUpdate(m_frame->localFrameRoot());
+
+  // Ensure the frame will be checked for paint invalidation during

[pdr., 2016/12/22 01:08:18]

Without spinvalidation, how are carets marked as needing paint invalidation?

It looks like we have some logic to invalidate them in
FrameCaret::invalidateCaretRect... are we missing a call to
"node->layoutObject()->setMayNeedPaintInvalidation" there, which would handle
crossing frames?

[Xianzhu, 2016/12/22 01:31:52]

Without spinvalidation, we always walk all of the FrameViews:
https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/frame/Fra....

Actually we could remove the walk for non-spinvalidation with unconditional
setMayNeedPaintInvalidation here. May consider a follow-up.

+  // PrePaintTreeWalk.
+  if (RuntimeEnabledFeatures::slimmingPaintInvalidationEnabled()) {
+    if (auto layoutItem = m_frame->ownerLayoutItem())

[pdr., 2016/12/22 01:08:18]

I think with LayoutItem you need to check !layoutItem.isNull().
Can you switch this to just using LayoutObject instead?
if (auto* layoutObject = m_frame->ownerLayoutObject())
    layoutObject->setMayNeedPaintInvalidation();

[Xianzhu, 2016/12/22 01:31:52]

The above is equivalent to "if (auto* layoutObject =
m_frame->ownerLayoutObject())", using LayoutItem::operator LayoutObject* (which
will be operator bool).

+      layoutItem.setMayNeedPaintInvalidation();
+  }
 }
 
 bool FrameCaret::caretPositionIsValidForDocument(