Add unittests for TTS controller pause/resume

This CL is adding unittests for the Pause(...) and Resume(...) API.
Fix potential bugs while calling pause/resume multiple times. The
underlying platform implementations may not accept double pause or
double resume.

The related code pause/resume was not covered by previous unittests.

Bug: 1133813
Change-Id: I396bed4e2356a3b4bcb8363f0f82d005436022bf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2446190
Commit-Queue: Etienne Bergeron <etienneb@chromium.org>
Reviewed-by: François Doray <fdoray@chromium.org>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#813430}

content/browser/speech/tts_controller_impl.cc

@@ -184,6 +184,8 @@ bool TtsControllerImpl::StopCurrentUtteranceIfMatches(const GURL& source_url) {
 
 void TtsControllerImpl::Pause() {
   base::RecordAction(base::UserMetricsAction("TextToSpeech.Pause"));
+  if (paused_)
+    return;
 
   paused_ = true;
   if (current_utterance_ && !current_utterance_->GetEngineId().empty()) {
@@ -197,6 +199,8 @@ void TtsControllerImpl::Pause() {
 
 void TtsControllerImpl::Resume() {
   base::RecordAction(base::UserMetricsAction("TextToSpeech.Resume"));
+  if (!paused_)
+    return;
 
   paused_ = false;
   if (current_utterance_ && !current_utterance_->GetEngineId().empty()) {
@@ -328,8 +332,7 @@ void TtsControllerImpl::RemoveUtteranceEventDelegate(
     }
 
     FinishCurrentUtterance();
-    if (!paused_)
-      SpeakNextUtterance();
+    SpeakNextUtterance();
   }
 }
 

content/browser/speech/tts_controller_impl.h

@@ -82,6 +82,9 @@ class CONTENT_EXPORT TtsControllerImpl : public TtsController,
   TtsControllerImpl();
   ~TtsControllerImpl() override;
 
+  // Exposed for unittest.
+  bool IsPausedForTesting() const { return paused_; }
+
  private:
   friend class TestTtsControllerImpl;
   friend struct base::DefaultSingletonTraits<TtsControllerImpl>;