Make WebSpellCheckClient aware of leak detection

components/test_runner/spell_check_client.cc

Index: components/test_runner/spell_check_client.cc
diff --git a/components/test_runner/spell_check_client.cc b/components/test_runner/spell_check_client.cc
index 68c663aa0a4c5763b5188bd66a62cccca9e0bf6d..83a837189cdb080729d745119bce4d37930f2f7f 100644
--- a/components/test_runner/spell_check_client.cc
+++ b/components/test_runner/spell_check_client.cc
@@ -96,6 +96,13 @@ void SpellCheckClient::requestCheckingOfText(
         0);
 }
 
+void SpellCheckClient::prepareForLeakDetection() {
+  if (!last_requested_text_checking_completion_)
+    return;
+  last_requested_text_checking_completion_->didCancelCheckingText();
+  last_requested_text_checking_completion_ = nullptr;
+}
+
 void SpellCheckClient::FinishLastTextCheck() {
   if (!last_requested_text_checking_completion_)
     return;