Explicit management of FrameSelection availability

third_party/WebKit/Source/core/editing/spellcheck/SpellChecker.cpp

Index: third_party/WebKit/Source/core/editing/spellcheck/SpellChecker.cpp
diff --git a/third_party/WebKit/Source/core/editing/spellcheck/SpellChecker.cpp b/third_party/WebKit/Source/core/editing/spellcheck/SpellChecker.cpp
index fa176f6a239d279acfd1c9a9ded9279efb361b98..2bc9902491fa39febb456a11e7810a95783016bc 100644
--- a/third_party/WebKit/Source/core/editing/spellcheck/SpellChecker.cpp
+++ b/third_party/WebKit/Source/core/editing/spellcheck/SpellChecker.cpp
@@ -563,9 +563,17 @@ void SpellChecker::chunkAndMarkAllMisspellingsAndBadGrammar(TextCheckingTypeMask
 void SpellChecker::markAndReplaceFor(SpellCheckRequest* request, const Vector<TextCheckingResult>& results)
 {
     TRACE_EVENT0("blink", "SpellChecker::markAndReplaceFor");
-    DCHECK(request);

[tkent, 2016/06/07 23:41:59]

Why do you remove the DCHECK?

[yosin_UTC9, 2016/06/08 04:06:10]

Oops, it should be here.

Done.

+    if (!frame().selection().isAvailable()) {
+        // "editing/spelling/spellcheck-async-remove-frame.html" reaches here.
+        return;
+    }
     if (!request->isValid())
         return;
+    if (request->rootEditableElement()->document() != frame().selection().document()) {
+        // we ignore |request| made for another document.
+        // "editing/spelling/spellcheck-sequencenum.html" and others reach here.
+        return;
+    }
 
     TextCheckingTypeMask textCheckingOptions = request->data().mask();
     TextCheckingParagraph paragraph(request->checkingRange(), request->paragraphRange());