[Idle time spell checker] Correct position passed from undo stack

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

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/editing/spellcheck/IdleSpellCheckCallback.h"
 
 #include "core/dom/IdleRequestOptions.h"
 #include "core/dom/TaskRunnerHelper.h"
 #include "core/editing/EditingUtilities.h"
 #include "core/editing/Editor.h"
@@ skipping 16 matching lines @@
 
 namespace {
 
 const int kColdModeTimerIntervalMS = 1000;
 const int kConsecutiveColdModeTimerIntervalMS = 200;
 const int kHotModeRequestTimeoutMS = 200;
 const int kInvalidHandle = -1;
 const int kDummyHandleForForcedInvocation = -2;
 const double kForcedInvocationDeadlineSeconds = 10;
 
+Position CorrectedReferencePosition(const Position& position,
+                                    const Document& document) {
+  if (!position.IsConnected() || position.GetDocument() != document)
+    return Position();
+  return CreateVisiblePosition(position).DeepEquivalent();
+}
+
 }  // namespace
 
 IdleSpellCheckCallback::~IdleSpellCheckCallback() {}
 
 DEFINE_TRACE(IdleSpellCheckCallback) {
   visitor->Trace(frame_);
   visitor->Trace(cold_mode_requester_);
   IdleRequestCallback::Trace(visitor);
   SynchronousMutationObserver::Trace(visitor);
 }
@@ skipping 101 matching lines @@
 
   const uint64_t watermark = last_processed_undo_step_sequence_;
   for (const UndoStep* step :
        GetFrame().GetEditor().GetUndoStack().UndoSteps()) {
     if (step->SequenceNumber() <= watermark)
       break;
     last_processed_undo_step_sequence_ =
         std::max(step->SequenceNumber(), last_processed_undo_step_sequence_);
     if (deadline->timeRemaining() == 0)
       break;
-    requester.CheckSpellingAt(step->EndingSelection().Extent());
+    // The reference position stored in undo stack can be invalid, disconnected
+    // or have been moved to another document, in which case it should be
+    // corrected.
+    const Position& stored_position = step->EndingSelection().Extent();
+    const Position& corrected_position =
+        CorrectedReferencePosition(stored_position, *GetFrame().GetDocument());
+    requester.CheckSpellingAt(corrected_position);
   }
 }
 
 void IdleSpellCheckCallback::handleEvent(IdleDeadline* deadline) {
   DCHECK(RuntimeEnabledFeatures::idleTimeSpellCheckingEnabled());
   DCHECK(GetFrame().GetDocument());
   DCHECK(GetFrame().GetDocument()->IsActive());
   DCHECK_NE(idle_callback_handle_, kInvalidHandle);
   idle_callback_handle_ = kInvalidHandle;
 
@@ skipping 59 matching lines @@
   DCHECK(cold_mode_timer_.IsActive());
   cold_mode_timer_.Stop();
   ColdModeTimerFired(&cold_mode_timer_);
 }
 
 void IdleSpellCheckCallback::SetNeedsMoreColdModeInvocationForTesting() {
   cold_mode_requester_->SetNeedsMoreInvocationForTesting();
 }
 
 }  // namespace blink