Audit the use of updateStyleAndLayoutIgnorePendingStylesheets in InputMethodController::setSelectio…

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

Index: third_party/WebKit/Source/core/editing/InputMethodController.cpp
diff --git a/third_party/WebKit/Source/core/editing/InputMethodController.cpp b/third_party/WebKit/Source/core/editing/InputMethodController.cpp
index bbd161bf33e0cc0389cf5a6d32762d8a1fefc3da..dee24b414adbe665f5adef145b5293df89a046ec 100644
--- a/third_party/WebKit/Source/core/editing/InputMethodController.cpp
+++ b/third_party/WebKit/Source/core/editing/InputMethodController.cpp
@@ -255,7 +255,13 @@ bool InputMethodController::confirmCompositionOrInsertText(const String& text, C
         return confirmComposition(composingText(), DoNotKeepSelection);
 
     SelectionOffsetsScope selectionOffsetsScope(this);
-    return confirmComposition();
+    bool result = confirmComposition();
+
+    // TODO(xiaochengh): The use of updateStyleAndLayoutIgnorePendingStylesheets
+    // needs to be audited. see http://crbug.com/590369 for more details.
+    frame().document()->updateStyleAndLayoutIgnorePendingStylesheets();

[yosin_UTC9, 2016/09/08 04:04:41]

This is the first pattern which updates layout after calling mutator.
Could you explain why do we do this?
I think we should avoid this pattern. 
Caller of |confirmCompositionOrInsertText()| should update layout.

[Xiaocheng, 2016/09/08 06:39:09]

It is in fact the dtor of the SelectionOffsetsScope that requires clean layout.
Is there anything we can do in this case?

+
+    return result;
 }
 
 void InputMethodController::cancelComposition()
@@ -354,6 +360,10 @@ void InputMethodController::setComposition(const String& text, const Vector<Comp
             TypingCommand::deleteSelection(*frame().document(), TypingCommand::PreventSpellChecking);
         }
 
+        // TODO(xiaochengh): The use of updateStyleAndLayoutIgnorePendingStylesheets
+        // needs to be audited. see http://crbug.com/590369 for more details.
+        frame().document()->updateStyleAndLayoutIgnorePendingStylesheets();
+
         setEditableSelectionOffsets(selectedRange);
         return;
     }
@@ -405,6 +415,10 @@ void InputMethodController::setComposition(const String& text, const Vector<Comp
     if (baseNode->layoutObject())
         baseNode->layoutObject()->setShouldDoFullPaintInvalidation();
 
+    // TODO(xiaochengh): The use of updateStyleAndLayoutIgnorePendingStylesheets
+    // needs to be audited. see http://crbug.com/590369 for more details.
+    frame().document()->updateStyleAndLayoutIgnorePendingStylesheets();
+
     // We shouldn't close typing in the middle of setComposition.
     setEditableSelectionOffsets(selectedRange, NotUserTriggered);
 
@@ -498,9 +512,7 @@ bool InputMethodController::setSelectionOffsets(const PlainTextRange& selectionO
     if (!rootEditableElement)
         return false;
 
-    // TODO(dglazkov): The use of updateStyleAndLayoutIgnorePendingStylesheets needs to be audited.
-    // see http://crbug.com/590369 for more details.
-    rootEditableElement->document().updateStyleAndLayoutIgnorePendingStylesheets();
+    DCHECK(!rootEditableElement->document().needsLayoutTreeUpdate());
 
     const EphemeralRange range = selectionOffsets.createRange(*rootEditableElement);
     if (range.isNull())