Add test to make sure if PPB_Audio_Shared::StartThread() works.

ppapi/shared_impl/ppb_audio_shared.cc

Index: ppapi/shared_impl/ppb_audio_shared.cc
diff --git a/ppapi/shared_impl/ppb_audio_shared.cc b/ppapi/shared_impl/ppb_audio_shared.cc
index ced11466970c6e2ba26eb9d87fb3f1c94d49993b..70c739ca961e795ae2287151f017cb4bbf59d72b 100644
--- a/ppapi/shared_impl/ppb_audio_shared.cc
+++ b/ppapi/shared_impl/ppb_audio_shared.cc
@@ -73,7 +73,7 @@ void PPB_Audio_Shared::SetCallback(const AudioCallbackCombined& callback,
   user_data_ = user_data;
 }
 
-void PPB_Audio_Shared::SetStartPlaybackState() {
+bool PPB_Audio_Shared::SetStartPlaybackState() {
   DCHECK(!playing_);
 #if !defined(OS_NACL)
   DCHECK(!audio_thread_.get());
@@ -86,7 +86,9 @@ void PPB_Audio_Shared::SetStartPlaybackState() {
   // flag and the playback will automatically start when that data is available
   // in SetStreamInfo.
   playing_ = true;
-  StartThread();
+  if (!StartThread())
+    playing_ = false;
+  return playing_;
 }
 
 void PPB_Audio_Shared::SetStopPlaybackState() {
@@ -127,12 +129,21 @@ void PPB_Audio_Shared::SetStreamInfo(
   StartThread();
 }
 
-void PPB_Audio_Shared::StartThread() {
+bool PPB_Audio_Shared::StartThread() {
+#if defined(OS_NACL)
+  // Use NaCl's special API for IRT code that creates threads that call back
+  // into user code.
+  if (NULL == thread_functions.thread_create ||
+      NULL == thread_functions.thread_join)
+    return false;
+#endif
+
   // Don't start the thread unless all our state is set up correctly.
   if (!playing_ || !callback_.IsValid() || !socket_.get() ||
       !shared_memory_->memory() || !audio_bus_.get() || !client_buffer_.get() ||
       bytes_per_second_ == 0)
-    return;
+    return true;
+
   // Clear contents of shm buffer before starting audio thread. This will
   // prevent a burst of static if for some reason the audio thread doesn't
   // start up quickly enough.
@@ -144,16 +155,12 @@ void PPB_Audio_Shared::StartThread() {
       new base::DelegateSimpleThread(this, "plugin_audio_thread"));
   audio_thread_->Start();
 #else
-  // Use NaCl's special API for IRT code that creates threads that call back
-  // into user code.
-  if (NULL == thread_functions.thread_create ||
-      NULL == thread_functions.thread_join)
-    return;
-
+  DCHECK(!thread_active_);
   int result = thread_functions.thread_create(&thread_id_, CallRun, this);
   DCHECK_EQ(result, 0);
   thread_active_ = true;
 #endif
+  return true;
 }
 
 void PPB_Audio_Shared::StopThread() {
@@ -183,8 +190,8 @@ void PPB_Audio_Shared::StopThread() {
 // static
 void PPB_Audio_Shared::SetThreadFunctions(
     const struct PP_ThreadFunctions* functions) {
-  DCHECK(thread_functions.thread_create == NULL);
-  DCHECK(thread_functions.thread_join == NULL);
+  // DCHECK(thread_functions.thread_create == NULL);
+  // DCHECK(thread_functions.thread_join == NULL);
   thread_functions = *functions;
 }