Ensure clean layout before calling LayoutText::CaretMaxOffset

LayoutText::CaretMaxOffset() requires clean layout, but currently can be
called from DeleteSelectionCommand when layout is dirty. This patch adds
layout update before the call sites to fix it.

Bug: 781698
Change-Id: I17b7596e93f025d61836e39cca4bf736713d3422
Reviewed-on: https://chromium-review.googlesource.com/778050
Commit-Queue: Xiaocheng Hu <xiaochengh@chromium.org>
Reviewed-by: Koji Ishii <kojii@chromium.org>
Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#517778}

third_party/WebKit/Source/core/editing/commands/DeleteSelectionCommand.cpp

@@ -618,6 +618,7 @@ void DeleteSelectionCommand::HandleGeneralDelete(EditingState* editing_state) {
       return;
   }
 
+  GetDocument().UpdateStyleAndLayoutIgnorePendingStylesheets();
   if (start_offset >= CaretMaxOffset(start_node) && start_node->IsTextNode()) {
     Text* text = ToText(start_node);
     if (text->length() > (unsigned)CaretMaxOffset(start_node))
@@ -698,6 +699,7 @@ void DeleteSelectionCommand::HandleGeneralDelete(EditingState* editing_state) {
           return;
         node = next_node;
       } else {
+        GetDocument().UpdateStyleAndLayoutIgnorePendingStylesheets();
         Node& n = NodeTraversal::LastWithinOrSelf(*node);
         if (downstream_end_.AnchorNode() == n &&
             downstream_end_.ComputeEditingOffset() >= CaretMaxOffset(&n)) {

third_party/WebKit/Source/core/layout/LayoutText.cpp

@@ -1962,6 +1962,9 @@ Optional<unsigned> LayoutText::CaretOffsetForPosition(
 }
 
 int LayoutText::CaretMinOffset() const {
+  // TODO(crbug.com/781698): Add the following DCHECK.
+  // DCHECK(!GetDocument().NeedsLayoutTreeUpdate());
+
   if (auto* mapping = GetNGOffsetMapping()) {
     const Position first_position = PositionForCaretOffset(0);
     if (first_position.IsNull())
@@ -1984,6 +1987,9 @@ int LayoutText::CaretMinOffset() const {
 }
 
 int LayoutText::CaretMaxOffset() const {
+  // TODO(crbug.com/781698): Add the following DCHECK.
+  // DCHECK(!GetDocument().NeedsLayoutTreeUpdate());
+
   if (auto* mapping = GetNGOffsetMapping()) {
     const Position last_position = PositionForCaretOffset(TextLength());
     if (last_position.IsNull())