Add a switch to TestRunner to enable/disable mock spell checker

components/test_runner/test_runner.h

Index: components/test_runner/test_runner.h
diff --git a/components/test_runner/test_runner.h b/components/test_runner/test_runner.h
index 1abf848ebd5b4d059a1539cf66f200dfe7b3e132..b394f97b85fbfd1e48c7d95758fa328a53df55fe 100644
--- a/components/test_runner/test_runner.h
+++ b/components/test_runner/test_runner.h
@@ -463,6 +463,9 @@ class TestRunner : public WebTestRunner {
   // to test output.
   void SetDumpConsoleMessages(bool value);
 
+  // Controls whether the mock spell checker is enabled.
+  void SetMockSpellCheckerEnabled(bool enabled);
+
   ///////////////////////////////////////////////////////////////////////////
   // Methods interacting with the WebViewTestProxy