Ensure valid VisiblePosition input for absoluteCaretBoundsOf

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

Index: third_party/WebKit/Source/core/editing/VisibleUnits.cpp
diff --git a/third_party/WebKit/Source/core/editing/VisibleUnits.cpp b/third_party/WebKit/Source/core/editing/VisibleUnits.cpp
index 6ab9347e7956955e656efcf9ca7369271f385b7e..2916f42d34ea534f485d3bcc3a4bf51a3cc11ec9 100644
--- a/third_party/WebKit/Source/core/editing/VisibleUnits.cpp
+++ b/third_party/WebKit/Source/core/editing/VisibleUnits.cpp
@@ -2936,8 +2936,7 @@ bool isVisuallyEquivalentCandidate(const PositionInFlatTree& position)
 template <typename Strategy>
 static IntRect absoluteCaretBoundsOfAlgorithm(const VisiblePositionTemplate<Strategy>& visiblePosition)
 {
-    // TODO(xiaochengh): Ensure that this function is called with a valid
-    // |visiblePosition|, and add |DCHECK(visiblePosition.isValid())|;
+    DCHECK(visiblePosition.isValid()) << visiblePosition;
     LayoutObject* layoutObject;
     LayoutRect localRect = localCaretRectOfPosition(visiblePosition.toPositionWithAffinity(), layoutObject);
     if (localRect.isEmpty() || !layoutObject)