Mixing audio with different latency requirements

content/renderer/media/audio_renderer_mixer_manager.h

Index: content/renderer/media/audio_renderer_mixer_manager.h
diff --git a/content/renderer/media/audio_renderer_mixer_manager.h b/content/renderer/media/audio_renderer_mixer_manager.h
index 5a93351fde6174afac4804c4d64cc533018c6f57..853732fd674c2b989d04c9d77a5a2ef772cf48d9 100644
--- a/content/renderer/media/audio_renderer_mixer_manager.h
+++ b/content/renderer/media/audio_renderer_mixer_manager.h
@@ -13,6 +13,7 @@
 #include "base/synchronization/lock.h"
 #include "content/common/content_export.h"
 #include "media/audio/audio_device_description.h"
+#include "media/base/audio_latency.h"
 #include "media/base/audio_parameters.h"
 #include "media/base/audio_renderer_mixer_pool.h"
 #include "media/base/output_device_info.h"
@@ -61,21 +62,20 @@ class CONTENT_EXPORT AudioRendererMixerManager
       int source_render_frame_id,
       int session_id,
       const std::string& device_id,
-      const url::Origin& security_origin);
+      const url::Origin& security_origin,
+      media::AudioLatency::LatencyType latency);
 
   // AudioRendererMixerPool implementation.
 
   media::AudioRendererMixer* GetMixer(
       int source_render_frame_id,
-      const media::AudioParameters& params,
+      const media::AudioParameters& input_params,
+      media::AudioLatency::LatencyType latency,
       const std::string& device_id,
       const url::Origin& security_origin,
       media::OutputDeviceStatus* device_status) final;
 
-  void ReturnMixer(int source_render_frame_id,
-                   const media::AudioParameters& params,
-                   const std::string& device_id,
-                   const url::Origin& security_origin) final;
+  void ReturnMixer(const media::AudioRendererMixer* mixer) final;
 
   media::OutputDeviceInfo GetOutputDeviceInfo(
       int source_render_frame_id,
@@ -95,11 +95,13 @@ class CONTENT_EXPORT AudioRendererMixerManager
   struct MixerKey {
     MixerKey(int source_render_frame_id,
              const media::AudioParameters& params,
+             media::AudioLatency::LatencyType latency,
              const std::string& device_id,
              const url::Origin& security_origin);
     MixerKey(const MixerKey& other);
     int source_render_frame_id;
     media::AudioParameters params;
+    media::AudioLatency::LatencyType latency;
     std::string device_id;
     url::Origin security_origin;
   };
@@ -124,14 +126,27 @@ class CONTENT_EXPORT AudioRendererMixerManager
         // Both device IDs represent the same default device => do not compare
         // them; the default device is always authorized => ignoring security
         // origin.
-        return false;
+        return CompareLatency(a, b);

[chcunningham, 2016/06/22 02:13:56]

Can you CompareLatency just once above this if and then keep the logic here and
below the same? Maybe I'm missing something subtle

[o1ka, 2016/06/23 16:36:15]

It's me who's missed something :)
Done.

       }
 
       if (a.device_id != b.device_id)
         return a.device_id < b.device_id;
 
+      if (a.security_origin == b.security_origin)
+        return CompareLatency(a, b);
+
       return a.security_origin < b.security_origin;
     }
+
+    bool CompareLatency(const MixerKey& a, const MixerKey& b) const {
+      // LATENCY_EXACT_MS can be mixed only with the same latency type and the
+      // same required buffer duration.
+      if ((a.latency == media::AudioLatency::LATENCY_EXACT_MS) &&
+          (b.latency == media::AudioLatency::LATENCY_EXACT_MS))
+        return a.params.GetBufferDuration() < b.params.GetBufferDuration();
+
+      return a.latency < b.latency;
+    }
   };
 
   // Map of MixerKey to <AudioRendererMixer, Count>.  Count allows