Fix race in audio playback.

components/copresence/handlers/audio/audio_directive_handler.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/copresence/handlers/audio/audio_directive_handler.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/string_util.h"
@@ skipping 104 matching lines @@
 // Private methods.
 
 void AudioDirectiveHandler::ProcessNextTransmit() {
   // If we have an active directive for audible or inaudible audio, ensure that
   // we are playing our respective token; if we do not have a directive, then
   // make sure we aren't playing. This is duplicate code, but for just two
   // elements, it has hard to make a case for processing a loop instead.
 
   scoped_ptr<AudioDirective> audible_transmit(
       transmits_list_audible_.GetActiveDirective());
-  if (audible_transmit && !player_audible_->IsPlaying()) {
+  if (audible_transmit && !player_audible_->IsPlaying() &&
+      samples_cache_audible_.HasKey(current_token_audible_)) {
     DVLOG(3) << "Playing audible for op_id: " << audible_transmit->op_id;
     player_audible_->Play(
         samples_cache_audible_.GetValue(current_token_audible_));
     stop_audible_playback_timer_.Start(
         FROM_HERE,
         audible_transmit->end_time - base::Time::Now(),
         this,
         &AudioDirectiveHandler::ProcessNextTransmit);
   } else if (!audible_transmit && player_audible_->IsPlaying()) {
     DVLOG(3) << "Stopping audible playback.";
     current_token_audible_.clear();
     stop_audible_playback_timer_.Stop();
     player_audible_->Stop();
   }
 
   scoped_ptr<AudioDirective> inaudible_transmit(
       transmits_list_inaudible_.GetActiveDirective());
-  if (inaudible_transmit && !player_inaudible_->IsPlaying()) {
+  if (inaudible_transmit && !player_inaudible_->IsPlaying() &&
+      samples_cache_inaudible_.HasKey(current_token_inaudible_)) {
     DVLOG(3) << "Playing inaudible for op_id: " << inaudible_transmit->op_id;
     player_inaudible_->Play(
         samples_cache_inaudible_.GetValue(current_token_inaudible_));
     stop_inaudible_playback_timer_.Start(
         FROM_HERE,
         inaudible_transmit->end_time - base::Time::Now(),
         this,
         &AudioDirectiveHandler::ProcessNextTransmit);
   } else if (!inaudible_transmit && player_inaudible_->IsPlaying()) {
     DVLOG(3) << "Stopping inaudible playback.";
@@ skipping 55 matching lines @@
     current_token_inaudible_ = token;
     // Force process transmits to pick up the new token.
     if (player_inaudible_->IsPlaying())
       player_inaudible_->Stop();
   }
 
   ProcessNextTransmit();
 }
 
 }  // namespace copresence