Handle repeated and overlapping (re)starts of mock speechrecognizer.

components/test_runner/mock_web_speech_recognizer.cc

Index: components/test_runner/mock_web_speech_recognizer.cc
diff --git a/components/test_runner/mock_web_speech_recognizer.cc b/components/test_runner/mock_web_speech_recognizer.cc
index f2527c1e8d44a82ff69a7235fb53d65c40c28473..88570b862668c305c0f3e544eda0340c4967819e 100644
--- a/components/test_runner/mock_web_speech_recognizer.cc
+++ b/components/test_runner/mock_web_speech_recognizer.cc
@@ -183,7 +183,7 @@ void MockWebSpeechRecognizer::start(
     const blink::WebSpeechRecognitionParams& params,
     blink::WebSpeechRecognizerClient* client) {
   was_aborted_ = false;
-  if (!client_) {
+  if (!client_ && !HasPendingNewContextTasks()) {
     handle_ = handle;
     client_ = client;
   } else {
@@ -318,4 +318,12 @@ void MockWebSpeechRecognizer::RunTaskFromQueue() {
   PostRunTaskFromQueue();
 }
 
+bool MockWebSpeechRecognizer::HasPendingNewContextTasks() const {
+  for (const auto& task : task_queue_) {
+    if (task->isNewContextTask())
+      return true;
+  }
+  return false;
+}
+
 }  // namespace test_runner