[Chromecast] Remove unused fields from CMA backend statistics

Separate Decoder::Statistics into audio and video-specific structs
so there are no unused fields.

BUG=internal b/25379144

Review URL: https://codereview.chromium.org/1528793003

Cr-Commit-Position: refs/heads/master@{#365370}

3 files changed, 31 insertions, 20 deletions

diff --git a/chromecast/media/cma/pipeline/audio_pipeline_impl.cc b/chromecast/media/cma/pipeline/audio_pipeline_impl.cc
index 2f051eb..5edc017 100644
--- a/chromecast/media/cma/pipeline/audio_pipeline_impl.cc
+++ b/chromecast/media/cma/pipeline/audio_pipeline_impl.cc
@@ -73,11 +73,11 @@ void AudioPipelineImpl::UpdateStatistics() {
   if (client().statistics_cb.is_null())
     return;
 
-  MediaPipelineBackend::Decoder::Statistics device_stats;
-  audio_decoder_->GetStatistics(&device_stats);
+  MediaPipelineBackend::AudioDecoder::Statistics audio_stats;
+  audio_decoder_->GetStatistics(&audio_stats);
 
   ::media::PipelineStatistics current_stats;
-  current_stats.audio_bytes_decoded = device_stats.decoded_bytes;
+  current_stats.audio_bytes_decoded = audio_stats.decoded_bytes;
 
   ::media::PipelineStatistics delta_stats;
   delta_stats.audio_bytes_decoded =
diff --git a/chromecast/media/cma/pipeline/video_pipeline_impl.cc b/chromecast/media/cma/pipeline/video_pipeline_impl.cc
index 61ec7dd..1888776 100644
--- a/chromecast/media/cma/pipeline/video_pipeline_impl.cc
+++ b/chromecast/media/cma/pipeline/video_pipeline_impl.cc
@@ -101,13 +101,13 @@ void VideoPipelineImpl::UpdateStatistics() {
   if (client().statistics_cb.is_null())
     return;
 
-  MediaPipelineBackend::Decoder::Statistics device_stats;
-  video_decoder_->GetStatistics(&device_stats);
+  MediaPipelineBackend::VideoDecoder::Statistics video_stats;
+  video_decoder_->GetStatistics(&video_stats);
 
   ::media::PipelineStatistics current_stats;
-  current_stats.video_bytes_decoded = device_stats.decoded_bytes;
-  current_stats.video_frames_decoded = device_stats.decoded_samples;
-  current_stats.video_frames_dropped = device_stats.dropped_samples;
+  current_stats.video_bytes_decoded = video_stats.decoded_bytes;
+  current_stats.video_frames_decoded = video_stats.decoded_frames;
+  current_stats.video_frames_dropped = video_stats.dropped_frames;
 
   ::media::PipelineStatistics delta_stats;
   delta_stats.video_bytes_decoded =
diff --git a/chromecast/public/media/media_pipeline_backend.h b/chromecast/public/media/media_pipeline_backend.h
index febd2523..d3739de 100644
--- a/chromecast/public/media/media_pipeline_backend.h
+++ b/chromecast/public/media/media_pipeline_backend.h
@@ -73,14 +73,6 @@ class MediaPipelineBackend {
       virtual ~Delegate() {}
     };
 
-    // Statistics (computed since pipeline last started playing).
-    // For video, a sample is defined as a frame.
-    struct Statistics {
-      uint64_t decoded_bytes;
-      uint64_t decoded_samples;
-      uint64_t dropped_samples;
-    };
-
     // Provides the delegate for this decoder. Called once before the backend
     // is initialized; is never called after the backend is initialized.
     virtual void SetDelegate(Delegate* delegate) = 0;
@@ -104,10 +96,6 @@ class MediaPipelineBackend {
     // calling OnPushBufferComplete() for kBufferPending case).
     virtual BufferStatus PushBuffer(CastDecoderBuffer* buffer) = 0;
 
-    // Returns the playback statistics since this decoder's creation.  Only
-    // called when playing or paused.
-    virtual void GetStatistics(Statistics* statistics) = 0;
-
    protected:
     virtual ~Decoder() {}
   };
@@ -128,6 +116,13 @@ class MediaPipelineBackend {
       int64_t timestamp_microseconds;
     };
 
+    // Statistics (computed since last call to backend Start).
+    struct Statistics {
+      // Reported as webkitAudioBytesDecoded.  Counts number of source bytes
+      // decoded (not decoder output bytes).
+      uint64_t decoded_bytes;
+    };
+
     // Provides the audio configuration.  Called once before the backend is
     // initialized, and again any time the configuration changes (in any state).
     // Note that SetConfig() may be called before SetDelegate() is called.
@@ -146,18 +141,34 @@ class MediaPipelineBackend {
     // Only called when the backend is playing.
     virtual RenderingDelay GetRenderingDelay() = 0;
 
+    // Returns the playback statistics since last call to backend Start.  Only
+    // called when playing or paused.
+    virtual void GetStatistics(Statistics* statistics) = 0;
+
    protected:
     ~AudioDecoder() override {}
   };
 
   class VideoDecoder : public Decoder {
    public:
+    // Statistics (computed since last call to backend Start).
+    struct Statistics {
+      // Counts number of source bytes decoded (not decoder output).
+      uint64_t decoded_bytes;  // Reported as webkitVideoBytesDecoded.
+      uint64_t decoded_frames;  // Reported as webkitDecodedFrames.
+      uint64_t dropped_frames;  // Reported as webkitDroppedFrames.
+    };
+
     // Provides the video configuration.  Called once before the backend is
     // initialized, and again any time the configuration changes (in any state).
     // Note that SetConfig() may be called before SetDelegate() is called.
     // Returns true if the configuration is a supported configuration.
     virtual bool SetConfig(const VideoConfig& config) = 0;
 
+    // Returns the playback statistics since last call to backend Start.  Only
+    // called when playing or paused.
+    virtual void GetStatistics(Statistics* statistics) = 0;
+
    protected:
     ~VideoDecoder() override {}
   };